[interpreter] Prepare for shipping --harmony-instanceof.

R=rmcilroy@chromium.org
TEST=cctest/test-interpreter/InterpreterInstanceOf
BUG=v8:4447
LOG=n

Review URL: https://codereview.chromium.org/1816063002

Cr-Commit-Position: refs/heads/master@{#34933}

src/compiler/ast-graph-builder.cc

@@ -2877,6 +2877,7 @@ void AstGraphBuilder::VisitCompareOperation(CompareOperation* expr) {
       op = javascript()->GreaterThanOrEqual();
       break;
     case Token::INSTANCEOF:
+      DCHECK(!FLAG_harmony_instanceof);
       op = javascript()->InstanceOf();
       break;
     case Token::IN:

src/compiler/bytecode-graph-builder.cc

@@ -1306,6 +1306,7 @@ void BytecodeGraphBuilder::VisitTestIn() {
 }
 
 void BytecodeGraphBuilder::VisitTestInstanceOf() {
+  DCHECK(!FLAG_harmony_instanceof);
   BuildCompareOp(javascript()->InstanceOf());
 }
 

src/interpreter/bytecode-array-builder.cc

@@ -1433,6 +1433,7 @@ Bytecode BytecodeArrayBuilder::BytecodeForCompareOperation(Token::Value op) {
     case Token::Value::GTE:
       return Bytecode::kTestGreaterThanOrEqual;
     case Token::Value::INSTANCEOF:
+      DCHECK(!FLAG_harmony_instanceof);
       return Bytecode::kTestInstanceOf;
     case Token::Value::IN:
       return Bytecode::kTestIn;

test/cctest/interpreter/test-interpreter.cc

@@ -1450,6 +1450,11 @@ TEST(InterpreterStrictNotEqual) {
 
 TEST(InterpreterInstanceOf) {
   HandleAndZoneScope handles;
+  // TODO(4447): The new ES6 'instanceof' operator is fully desugared in the
+  // parser and the Token::INSTANCEOF is not needed anymore. This test only
+  // makes sense with --no-harmony-instanceof and can be removed once we
+  // deprecate the ability to switch to old skool ES5 'instanceof' for good.
+  FLAG_harmony_instanceof = false;
   i::Factory* factory = handles.main_isolate()->factory();
   Handle<i::String> name = factory->NewStringFromAsciiChecked("cons");
   Handle<i::JSFunction> func = factory->NewFunction(name);