Use counter for legacy const.

test/cctest/test-parsing.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 3423 matching lines @@
   global_use_counts = use_counts;
   CcTest::isolate()->SetUseCounterCallback(MockUseCounterCallback);
   CompileRun("\"use asm\";\n"
              "var foo = 1;\n"
              "\"use asm\";\n"  // Only the first one counts.
              "function bar() { \"use asm\"; var baz = 1; }");
   CHECK_EQ(2, use_counts[v8::Isolate::kUseAsm]);
 }
 
 
+TEST(UseConstLegacyCount) {
+  i::Isolate* isolate = CcTest::i_isolate();
+  i::HandleScope scope(isolate);
+  LocalContext env;
+  int use_counts[v8::Isolate::kUseCounterFeatureCount] = {};
+  global_use_counts = use_counts;
+  CcTest::isolate()->SetUseCounterCallback(MockUseCounterCallback);
+  CompileRun(
+      "const x = 1;\n"
+      "var foo = 1;\n"
+      "const y = 1;\n"
+      "function bar() {\n"
+      "    const z = 1; var baz = 1;\n"
+      "    function q() { const k = 42; }\n"
+      "}");
+  CHECK_EQ(4, use_counts[v8::Isolate::kLegacyConst]);
+}
+
+
 TEST(ErrorsArrowFunctions) {
   // Tests that parser and preparser generate the same kind of errors
   // on invalid arrow function syntax.
   const char* context_data[][2] = {
     {"", ";"},
     {"v = ", ";"},
     {"bar ? (", ") : baz;"},
     {"bar ? baz : (", ");"},
     {"bar[", "];"},
     {"bar, ", ";"},
@@ skipping 2327 matching lines @@
     v8::Script::Compile(v8_str(script3));
     CHECK(try_catch2.HasCaught());
     v8::String::Utf8Value exception(try_catch2.Exception());
     CHECK_EQ(0,
              strcmp(
                  "ReferenceError: In strong mode, using an undeclared global "
                  "variable 'not_there3' is not allowed",
                  *exception));
   }
 }