[es6] Implement spec compliant ToPrimitive in the runtime.

src/full-codegen/mips/full-codegen-mips.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #if V8_TARGET_ARCH_MIPS
 
 // Note on Mips implementation:
 //
 // The result_register() for mips is the 'v0' register, which is defined
 // by the ABI to contain function return values. However, the first
@@ skipping 3444 matching lines @@
   __ Addu(t0, t0, Operand(DescriptorArray::kFirstOffset - kHeapObjectTag));
   // Calculate the end of the descriptor array.
   __ mov(a2, t0);
   __ sll(t1, a3, kPointerSizeLog2);
   __ Addu(a2, a2, t1);
 
   // Loop through all the keys in the descriptor array. If one of these is the
   // string "valueOf" the result is false.
   // The use of t2 to store the valueOf string assumes that it is not otherwise
   // used in the loop below.
-  __ li(t2, Operand(isolate()->factory()->value_of_string()));
+  __ LoadRoot(t2, Heap::kvalueOf_stringRootIndex);
   __ jmp(&entry);
   __ bind(&loop);
   __ lw(a3, MemOperand(t0, 0));
   __ Branch(if_false, eq, a3, Operand(t2));
   __ Addu(t0, t0, Operand(DescriptorArray::kDescriptorSize * kPointerSize));
   __ bind(&entry);
   __ Branch(&loop, ne, t0, Operand(a2));
 
   __ bind(&done);
 
@@ skipping 1867 matching lines @@
          reinterpret_cast<uint32_t>(
              isolate->builtins()->OsrAfterStackCheck()->entry()));
   return OSR_AFTER_STACK_CHECK;
 }
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_MIPS