Reland 10216 - Optimize the equality check case of ICCompare stubs.

src/ia32/ic-ia32.cc

Index: src/ia32/ic-ia32.cc
===================================================================
--- src/ia32/ic-ia32.cc	(revision 10217)
+++ src/ia32/ic-ia32.cc	(working copy)
@@ -1625,6 +1625,9 @@
     rewritten = stub.GetCode();
   } else {
     ICCompareStub stub(op_, state);
+    if (state == KNOWN_OBJECTS) {
+      stub.set_known_map(Handle<Map>(Handle<JSObject>::cast(x)->map()));
+    }
     rewritten = stub.GetCode();
   }
   set_target(*rewritten);