Add complete ElementKind information directly to Map for objects with elements.

src/arm/macro-assembler-arm.cc

Index: src/arm/macro-assembler-arm.cc
diff --git a/src/arm/macro-assembler-arm.cc b/src/arm/macro-assembler-arm.cc
index 412091d129e8247d38df4be8e519c948d2aae426..dc9042612b0a9e04d36e7df854b644cd5f1850bf 100644
--- a/src/arm/macro-assembler-arm.cc
+++ b/src/arm/macro-assembler-arm.cc
@@ -1677,6 +1677,16 @@ void MacroAssembler::CompareRoot(Register obj,
 }
 
 
+void MacroAssembler::CheckFastElements(Register map,
+                                       Register scratch,
+                                       Label* fail) {
+  STATIC_ASSERT(JSObject::FAST_ELEMENTS == 0);
+  ldrb(scratch, FieldMemOperand(map, Map::kInstanceTypeOffset));
+  cmp(scratch, Operand(Map::kMaximumBitField2FastElementValue));
+  b(hi, fail);
+}
+
+
 void MacroAssembler::CheckMap(Register obj,
                               Register scratch,
                               Handle<Map> map,