Reland "Fix phis for non-sse2 double values"

src/ia32/macro-assembler-ia32.cc

 // 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 2780 matching lines @@
     add(esp, Immediate(bytes_dropped));
     push(scratch);
     ret(0);
   }
 }
 
 
 void MacroAssembler::VerifyX87StackDepth(uint32_t depth) {
   // Make sure the floating point stack is either empty or has depth items.
   ASSERT(depth <= 7);
+  // This is a very expensive.
+  ASSERT(FLAG_debug_code && FLAG_enable_slow_asserts);
 
   // The top-of-stack (tos) is 7 if there is one item pushed.
   int tos = (8 - depth) % 8;
   const int kTopMask = 0x3800;
   push(eax);
   fwait();
   fnstsw_ax();
   and_(eax, kTopMask);
   shr(eax, 11);
   cmp(eax, Immediate(tos));
@@ skipping 611 matching lines @@
   j(greater, &no_memento_available);
   cmp(MemOperand(scratch_reg, -AllocationMemento::kSize),
       Immediate(Handle<Map>(isolate()->heap()->allocation_memento_map())));
   bind(&no_memento_available);
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32