Merge r6983 to the 2.5 branch

src/arm/codegen-arm.cc

Index: src/arm/codegen-arm.cc
===================================================================
--- src/arm/codegen-arm.cc	(revision 6985)
+++ src/arm/codegen-arm.cc	(working copy)
@@ -5161,11 +5161,11 @@
 
     // Set the bit in the map to indicate that it has been checked safe for
     // default valueOf and set true result.
-    __ ldr(scratch1_, FieldMemOperand(map_result_, Map::kBitField2Offset));
+    __ ldrb(scratch1_, FieldMemOperand(map_result_, Map::kBitField2Offset));
     __ orr(scratch1_,
            scratch1_,
            Operand(1 << Map::kStringWrapperSafeForDefaultValueOf));
-    __ str(scratch1_, FieldMemOperand(map_result_, Map::kBitField2Offset));
+    __ strb(scratch1_, FieldMemOperand(map_result_, Map::kBitField2Offset));
     __ mov(map_result_, Operand(1));
     __ jmp(exit_label());
     __ bind(&false_result);