Use weak cells in map checks in polymorphic ICs.

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 729ce02527f44730c52bb3cfb623203c68fd5091..e45ae5c24c656b86eb785a46f50c82b07689e623 100644
--- a/src/arm/macro-assembler-arm.cc
+++ b/src/arm/macro-assembler-arm.cc
@@ -2269,6 +2269,22 @@ void MacroAssembler::DispatchMap(Register obj,
 }
 
 
+void MacroAssembler::CmpWeakValue(Register value, Handle<WeakCell> cell,
+                                  Register scratch) {
+  mov(scratch, Operand(cell));
+  ldr(scratch, FieldMemOperand(scratch, WeakCell::kValueOffset));
+  cmp(value, scratch);
+}
+
+
+void MacroAssembler::LoadWeakValue(Register value, Handle<WeakCell> cell,
+                                   Label* miss) {
+  mov(value, Operand(cell));
+  ldr(value, FieldMemOperand(value, WeakCell::kValueOffset));
+  JumpIfSmi(value, miss);
+}
+
+
 void MacroAssembler::TryGetFunctionPrototype(Register function,
                                              Register result,
                                              Register scratch,