Better support for 'polymorphic' JS and external arrays

src/ia32/macro-assembler-ia32.cc

Index: src/ia32/macro-assembler-ia32.cc
diff --git a/src/ia32/macro-assembler-ia32.cc b/src/ia32/macro-assembler-ia32.cc
index 7b2f6cf9d79c01c444c928456579712409471994..f38e2eefa6c4cd9669cbf236e8f4af0bce4b49b8 100644
--- a/src/ia32/macro-assembler-ia32.cc
+++ b/src/ia32/macro-assembler-ia32.cc
@@ -286,6 +286,21 @@ void MacroAssembler::CheckMap(Register obj,
 }
 
 
+void MacroAssembler::DispatchMap(Register obj,
+                                 Handle<Map> map,
+                                 Handle<Code> success,
+                                 SmiCheckType smi_check_type) {
+  Label fail;
+  if (smi_check_type == DONT_DO_SMI_CHECK) {
+    JumpIfSmi(obj, &fail);
+  }
+  cmp(FieldOperand(obj, HeapObject::kMapOffset), Immediate(map));
+  j(equal, success);
+
+  bind(&fail);
+}
+
+
 Condition MacroAssembler::IsObjectStringType(Register heap_object,
                                              Register map,
                                              Register instance_type) {