[Interpreter] Optimize code of the form 'if (x === undefined)'.

src/interpreter/mkpeephole.cc

Index: src/interpreter/mkpeephole.cc
diff --git a/src/interpreter/mkpeephole.cc b/src/interpreter/mkpeephole.cc
index e6c3b76f2808b19c6a6b36fffd9188113d4ca437..62d3a77e02c7faf513f1d8ff020217b6fd4785dd 100644
--- a/src/interpreter/mkpeephole.cc
+++ b/src/interpreter/mkpeephole.cc
@@ -192,28 +192,6 @@ PeepholeActionAndData PeepholeActionTableWriter::LookupActionAndData(
     }
   }
 
-  // Fuse LdaNull/LdaUndefined followed by a equality comparison with test
-  // undetectable. Testing undetectable is a simple check on the map which is
-  // more efficient than the full comparison operation.
-  if (last == Bytecode::kLdaNull || last == Bytecode::kLdaUndefined) {
-    if (current == Bytecode::kTestEqual) {
-      return {PeepholeAction::kTransformEqualityWithNullOrUndefinedAction,
-              Bytecode::kTestUndetectable};
-    }
-  }
-
-  // Fuse LdaNull/LdaUndefined followed by a strict equals with
-  // TestNull/TestUndefined.
-  if (current == Bytecode::kTestEqualStrict) {
-    if (last == Bytecode::kLdaNull) {
-      return {PeepholeAction::kTransformEqualityWithNullOrUndefinedAction,
-              Bytecode::kTestNull};
-    } else if (last == Bytecode::kLdaUndefined) {
-      return {PeepholeAction::kTransformEqualityWithNullOrUndefinedAction,
-              Bytecode::kTestUndefined};
-    }
-  }
-
   // If there is no last bytecode to optimize against, store the incoming
   // bytecode or for jumps emit incoming bytecode immediately.
   if (last == Bytecode::kIllegal) {