Reland "Track field types.".

src/ia32/lithium-codegen-ia32.cc

Index: src/ia32/lithium-codegen-ia32.cc
diff --git a/src/ia32/lithium-codegen-ia32.cc b/src/ia32/lithium-codegen-ia32.cc
index ebd430c788b587ac5144414d42fc8d7be099becf..fad23ade32c6e6c22ff6bd70461a9921756be0da 100644
--- a/src/ia32/lithium-codegen-ia32.cc
+++ b/src/ia32/lithium-codegen-ia32.cc
@@ -4406,7 +4406,7 @@ void LCodeGen::DoStoreNamedField(LStoreNamedField* instr) {
         __ test(value, Immediate(kSmiTagMask));
         DeoptimizeIf(zero, instr->environment());
 
-        // We know that value is a smi now, so we can omit the check below.
+        // We know now that value is not a smi, so we can omit the check below.
         check_needed = OMIT_SMI_CHECK;
       }
     }