Implement Math.random() purely in JavaScript.

src/runtime.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 600 matching lines @@
   F(ArgumentsLength, 0, 1)                                                   \
   F(Arguments, 1, 1)                                                         \
   F(ValueOf, 1, 1)                                                           \
   F(SetValueOf, 2, 1)                                                        \
   F(DateField, 2 /* date object, field index */, 1)                          \
   F(StringCharFromCode, 1, 1)                                                \
   F(StringCharAt, 2, 1)                                                      \
   F(OneByteSeqStringSetChar, 3, 1)                                           \
   F(TwoByteSeqStringSetChar, 3, 1)                                           \
   F(ObjectEquals, 2, 1)                                                      \
-  F(RandomHeapNumber, 0, 1)                                                  \
   F(IsObject, 1, 1)                                                          \
   F(IsFunction, 1, 1)                                                        \
   F(IsUndetectableObject, 1, 1)                                              \
   F(IsSpecObject, 1, 1)                                                      \
   F(IsStringWrapperSafeForDefaultValueOf, 1, 1)                              \
   F(MathPow, 2, 1)                                                           \
   F(MathSin, 1, 1)                                                           \
   F(MathCos, 1, 1)                                                           \
   F(MathTan, 1, 1)                                                           \
   F(MathSqrt, 1, 1)                                                          \
@@ skipping 210 matching lines @@
 //---------------------------------------------------------------------------
 // Constants used by interface to runtime functions.
 
 class DeclareGlobalsEvalFlag:     public BitField<bool,         0, 1> {};
 class DeclareGlobalsNativeFlag:   public BitField<bool,         1, 1> {};
 class DeclareGlobalsLanguageMode: public BitField<LanguageMode, 2, 2> {};
 
 } }  // namespace v8::internal
 
 #endif  // V8_RUNTIME_H_