Replace HeapNumber as doublebox with an explicit MutableHeapNumber.

src/ia32/macro-assembler-ia32.h

Index: src/ia32/macro-assembler-ia32.h
diff --git a/src/ia32/macro-assembler-ia32.h b/src/ia32/macro-assembler-ia32.h
index 698c81fe833f07250ff2749582560ddccee5e625..cc47317b654747124aa728a80aa5909488356bbe 100644
--- a/src/ia32/macro-assembler-ia32.h
+++ b/src/ia32/macro-assembler-ia32.h
@@ -645,6 +645,15 @@ class MacroAssembler: public Assembler {
                           Register scratch2,
                           Label* gc_required);
 
+  // Allocate a mutable heap number in new space with undefined value. The
+  // register scratch2 can be passed as no_reg; the others must be valid
+  // registers. Returns tagged pointer in result register, or jumps to
+  // gc_required if new space is full.
+  void AllocateMutableHeapNumber(Register result,

[Igor Sheludko, 2014/03/27 11:30:16]

What about other platforms we support?

+                                 Register scratch1,
+                                 Register scratch2,
+                                 Label* gc_required);
+
   // Allocate a sequential string. All the header fields of the string object
   // are initialized.
   void AllocateTwoByteString(Register result,