diff --git a/mfbt/double-conversion/double-conversion/double-conversion.h b/mfbt/double-conversion/double-conversion/double-conversion.h
--- a/mfbt/double-conversion/double-conversion/double-conversion.h
+++ b/mfbt/double-conversion/double-conversion/double-conversion.h
@@ -23,16 +23,17 @@
 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 #ifndef DOUBLE_CONVERSION_DOUBLE_CONVERSION_H_
 #define DOUBLE_CONVERSION_DOUBLE_CONVERSION_H_
 
+#include "mozilla/Types.h"
 #include <double-conversion/utils.h>
 
 namespace double_conversion {
 
 class DoubleToStringConverter {
  public:
   // When calling ToFixed with a double > 10^kMaxFixedDigitsBeforePoint
   // or a requested_digits parameter > kMaxFixedDigitsAfterPoint then the
@@ -124,17 +125,17 @@ class DoubleToStringConverter {
             max_trailing_padding_zeroes_in_precision_mode) {
     // When 'trailing zero after the point' is set, then 'trailing point'
     // must be set too.
     ASSERT(((flags & EMIT_TRAILING_DECIMAL_POINT) != 0) ||
         !((flags & EMIT_TRAILING_ZERO_AFTER_POINT) != 0));
   }
 
   // Returns a converter following the EcmaScript specification.
-  static const DoubleToStringConverter& EcmaScriptConverter();
+  static MFBT_API const DoubleToStringConverter& EcmaScriptConverter();
 
   // Computes the shortest string of digits that correctly represent the input
   // number. Depending on decimal_in_shortest_low and decimal_in_shortest_high
   // (see constructor) it then either returns a decimal representation, or an
   // exponential representation.
   // Example with decimal_in_shortest_low = -6,
   //              decimal_in_shortest_high = 21,
   //              EMIT_POSITIVE_EXPONENT_SIGN activated, and
@@ -192,17 +193,17 @@ class DoubleToStringConverter {
   // except for the following cases:
   //   - the input value is special and no infinity_symbol or nan_symbol has
   //     been provided to the constructor,
   //   - 'value' > 10^kMaxFixedDigitsBeforePoint, or
   //   - 'requested_digits' > kMaxFixedDigitsAfterPoint.
   // The last two conditions imply that the result will never contain more than
   // 1 + kMaxFixedDigitsBeforePoint + 1 + kMaxFixedDigitsAfterPoint characters
   // (one additional character for the sign, and one for the decimal point).
-  bool ToFixed(double value,
+  MFBT_API bool ToFixed(double value,
                int requested_digits,
                StringBuilder* result_builder) const;
 
   // Computes a representation in exponential format with requested_digits
   // after the decimal point. The last emitted digit is rounded.
   // If requested_digits equals -1, then the shortest exponential representation
   // is computed.
   //
@@ -224,17 +225,17 @@ class DoubleToStringConverter {
   // except for the following cases:
   //   - the input value is special and no infinity_symbol or nan_symbol has
   //     been provided to the constructor,
   //   - 'requested_digits' > kMaxExponentialDigits.
   // The last condition implies that the result will never contain more than
   // kMaxExponentialDigits + 8 characters (the sign, the digit before the
   // decimal point, the decimal point, the exponent character, the
   // exponent's sign, and at most 3 exponent digits).
-  bool ToExponential(double value,
+  MFBT_API bool ToExponential(double value,
                      int requested_digits,
                      StringBuilder* result_builder) const;
 
   // Computes 'precision' leading digits of the given 'value' and returns them
   // either in exponential or decimal format, depending on
   // max_{leading|trailing}_padding_zeroes_in_precision_mode (given to the
   // constructor).
   // The last computed digit is rounded.
@@ -262,17 +263,17 @@ class DoubleToStringConverter {
   // except for the following cases:
   //   - the input value is special and no infinity_symbol or nan_symbol has
   //     been provided to the constructor,
   //   - precision < kMinPericisionDigits
   //   - precision > kMaxPrecisionDigits
   // The last condition implies that the result will never contain more than
   // kMaxPrecisionDigits + 7 characters (the sign, the decimal point, the
   // exponent character, the exponent's sign, and at most 3 exponent digits).
-  bool ToPrecision(double value,
+  MFBT_API bool ToPrecision(double value,
                    int precision,
                    StringBuilder* result_builder) const;
 
   enum DtoaMode {
     // Produce the shortest correct representation.
     // For example the output of 0.299999999999999988897 is (the less accurate
     // but correct) 0.3.
     SHORTEST,
@@ -287,17 +288,17 @@ class DoubleToStringConverter {
   };
 
   // The maximal number of digits that are needed to emit a double in base 10.
   // A higher precision can be achieved by using more digits, but the shortest
   // accurate representation of any double will never use more digits than
   // kBase10MaximalLength.
   // Note that DoubleToAscii null-terminates its input. So the given buffer
   // should be at least kBase10MaximalLength + 1 characters long.
-  static const int kBase10MaximalLength = 17;
+  static const MFBT_DATA int kBase10MaximalLength = 17;
 
   // Converts the given double 'v' to digit characters. 'v' must not be NaN,
   // +Infinity, or -Infinity. In SHORTEST_SINGLE-mode this restriction also
   // applies to 'v' after it has been casted to a single-precision float. That
   // is, in this mode static_cast<float>(v) must not be NaN, +Infinity or
   // -Infinity.
   //
   // The result should be interpreted as buffer * 10^(point-length).
@@ -332,44 +333,44 @@ class DoubleToStringConverter {
   // DoubleToAscii expects the given buffer to be big enough to hold all
   // digits and a terminating null-character. In SHORTEST-mode it expects a
   // buffer of at least kBase10MaximalLength + 1. In all other modes the
   // requested_digits parameter and the padding-zeroes limit the size of the
   // output. Don't forget the decimal point, the exponent character and the
   // terminating null-character when computing the maximal output size.
   // The given length is only used in debug mode to ensure the buffer is big
   // enough.
-  static void DoubleToAscii(double v,
+  static MFBT_API void DoubleToAscii(double v,
                             DtoaMode mode,
                             int requested_digits,
                             char* buffer,
                             int buffer_length,
                             bool* sign,
                             int* length,
                             int* point);
 
  private:
   // Implementation for ToShortest and ToShortestSingle.
-  bool ToShortestIeeeNumber(double value,
+  MFBT_API bool ToShortestIeeeNumber(double value,
                             StringBuilder* result_builder,
                             DtoaMode mode) const;
 
   // If the value is a special value (NaN or Infinity) constructs the
   // corresponding string using the configured infinity/nan-symbol.
   // If either of them is NULL or the value is not special then the
   // function returns false.
-  bool HandleSpecialValues(double value, StringBuilder* result_builder) const;
+  MFBT_API bool HandleSpecialValues(double value, StringBuilder* result_builder) const;
   // Constructs an exponential representation (i.e. 1.234e56).
   // The given exponent assumes a decimal point after the first decimal digit.
-  void CreateExponentialRepresentation(const char* decimal_digits,
+  MFBT_API void CreateExponentialRepresentation(const char* decimal_digits,
                                        int length,
                                        int exponent,
                                        StringBuilder* result_builder) const;
   // Creates a decimal representation (i.e 1234.5678).
-  void CreateDecimalRepresentation(const char* decimal_digits,
+  MFBT_API void CreateDecimalRepresentation(const char* decimal_digits,
                                    int length,
                                    int decimal_point,
                                    int digits_after_point,
                                    StringBuilder* result_builder) const;
 
   const int flags_;
   const char* const infinity_symbol_;
   const char* const nan_symbol_;
