The check for internalized strings relied on the fact that we had less

src/arm/macro-assembler-arm.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 3071 matching lines @@
   and_(scratch1, first, Operand(second));
   JumpIfSmi(scratch1, failure);
   JumpIfNonSmisNotBothSequentialAsciiStrings(first,
                                              second,
                                              scratch1,
                                              scratch2,
                                              failure);
 }
 
 
+void MacroAssembler::JumpIfNotUniqueName(Register reg,
+                                         Label* not_unique_name) {
+  STATIC_ASSERT(((SYMBOL_TYPE - 1) & kIsInternalizedMask) == kInternalizedTag);
+  cmp(reg, Operand(kInternalizedTag));
+  b(lt, not_unique_name);
+  cmp(reg, Operand(SYMBOL_TYPE));
+  b(gt, not_unique_name);
+}
+
+
 // Allocates a heap number or jumps to the need_gc label if the young space
 // is full and a scavenge is needed.
 void MacroAssembler::AllocateHeapNumber(Register result,
                                         Register scratch1,
                                         Register scratch2,
                                         Register heap_number_map,
                                         Label* gc_required,
                                         TaggingMode tagging_mode) {
   // Allocate an object in the heap for the heap number and tag it as a heap
   // object.
@@ skipping 714 matching lines @@
 void CodePatcher::EmitCondition(Condition cond) {
   Instr instr = Assembler::instr_at(masm_.pc_);
   instr = (instr & ~kCondMask) | cond;
   masm_.emit(instr);
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_ARM