[parser] Remove incorrect UseCounter code for LabeledExpressionStatement

As noted in the attached bug, accurately counting this would require
significant changes to the parser and is thus infeasible.

Bug: v8:7211
Change-Id: I61f14c948f50e0f97e596a9696d72a3570ad588a
Reviewed-on: https://chromium-review.googlesource.com/853214Reviewed-by: Sathya Gunasekaran <gsathya@chromium.org>
Commit-Queue: Adam Klein <adamk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#50393}

src/parsing/parser-base.h

@@ -5176,11 +5176,6 @@ ParserBase<Impl>::ParseExpressionOrLabelledStatement(
 
   // Parsed expression statement, followed by semicolon.
   ExpectSemicolon(CHECK_OK);
-  if (labels != nullptr) {
-    // TODO(adamk): Also measure in the PreParser by passing something
-    // non-null as |labels|.
-    impl()->CountUsage(v8::Isolate::kLabeledExpressionStatement);
-  }
   return factory()->NewExpressionStatement(expr, pos);
 }
 

test/cctest/test-usecounters.cc

@@ -60,31 +60,6 @@ TEST(AssigmentExpressionLHSIsCall) {
   use_counts[v8::Isolate::kAssigmentExpressionLHSIsCallInStrict] = 0;
 }
 
-TEST(LabeledExpressionStatement) {
-  v8::Isolate* isolate = CcTest::isolate();
-  v8::HandleScope scope(isolate);
-  LocalContext env;
-  int use_counts[v8::Isolate::kUseCounterFeatureCount] = {};
-  global_use_counts = use_counts;
-  CcTest::isolate()->SetUseCounterCallback(MockUseCounterCallback);
-
-  CompileRun("typeof a");
-  CHECK_EQ(0, use_counts[v8::Isolate::kLabeledExpressionStatement]);
-
-  CompileRun("foo: null");
-  CHECK_EQ(1, use_counts[v8::Isolate::kLabeledExpressionStatement]);
-
-  CompileRun("foo: bar: baz: undefined");
-  CHECK_EQ(2, use_counts[v8::Isolate::kLabeledExpressionStatement]);
-
-  CompileRun(
-      "foo: if (false);"
-      "bar: { }"
-      "baz: switch (false) { }"
-      "bat: do { } while (false);");
-  CHECK_EQ(2, use_counts[v8::Isolate::kLabeledExpressionStatement]);
-}
-
 }  // namespace test_usecounters
 }  // namespace internal
 }  // namespace v8