Fix a potential crash bug in keyed calls for non-string keys.

src/x64/macro-assembler-x64.cc

 // Copyright 2010 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 1592 matching lines @@
 }
 
 
 void MacroAssembler::AbortIfNotSmi(Register object) {
   NearLabel ok;
   Condition is_smi = CheckSmi(object);
   Assert(is_smi, "Operand is not a smi");
 }
 
 
+void MacroAssembler::AbortIfNotString(Register object) {
+  testb(object, Immediate(kSmiTagMask));
+  Assert(not_equal, "Operand is not a string");
+  push(object);
+  movq(object, FieldOperand(object, HeapObject::kMapOffset));
+  CmpInstanceType(object, FIRST_NONSTRING_TYPE);
+  pop(object);
+  Assert(below, "Operand is not a string");
+}
+
+
 void MacroAssembler::AbortIfNotRootValue(Register src,
                                          Heap::RootListIndex root_value_index,
                                          const char* message) {
   ASSERT(!src.is(kScratchRegister));
   LoadRoot(kScratchRegister, root_value_index);
   cmpq(src, kScratchRegister);
   Check(equal, message);
 }
 
 
@@ skipping 867 matching lines @@
   CPU::FlushICache(address_, size_);
 
   // Check that the code was patched as expected.
   ASSERT(masm_.pc_ == address_ + size_);
   ASSERT(masm_.reloc_info_writer.pos() == address_ + size_ + Assembler::kGap);
 }
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64