[counters] Add UseCounters for 'f() = 0' syntax

src/parsing/parser-base.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_PARSING_PARSER_BASE_H
 #define V8_PARSING_PARSER_BASE_H
 
 #include "src/ast/ast.h"
 #include "src/ast/scopes.h"
 #include "src/bailout-reason.h"
@@ skipping 4313 matching lines @@
     ReportMessageAt(Scanner::Location(beg_pos, end_pos),
                     MessageTemplate::kStrictEvalArguments, kSyntaxError);
     *ok = false;
     return impl()->EmptyExpression();
   }
   if (expression->IsValidReferenceExpression()) {
     return expression;
   }
   if (expression->IsCall()) {
     // If it is a call, make it a runtime error for legacy web compatibility.
     // Rewrite `expr' to `expr[throw ReferenceError]'.

[Dan Ehrenberg, 2016/12/23 07:56:52]

Could you put a reference to
https://bugs.chromium.org/p/v8/issues/detail?id=4480 here?

[bakkot1, 2016/12/23 09:41:53]

Done.

+    impl()->CountUsage(
+        is_strict(language_mode())

[Dan Ehrenberg, 2016/12/23 07:56:52]

Aren't you glad we don't have strong mode?

+            ? v8::Isolate::kAssigmentExpressionLHSIsCallInStrict
+            : v8::Isolate::kAssigmentExpressionLHSIsCallInNonstrict);
     ExpressionT error = impl()->NewThrowReferenceError(message, beg_pos);
     return factory()->NewProperty(expression, error, beg_pos);
   }
   ReportMessageAt(Scanner::Location(beg_pos, end_pos), message, type);
   *ok = false;
   return impl()->EmptyExpression();
 }
 
 template <typename Impl>
 bool ParserBase<Impl>::IsValidReferenceExpression(ExpressionT expression) {
@@ skipping 1148 matching lines @@
     has_seen_constructor_ = true;
     return;
   }
 }
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_PARSING_PARSER_BASE_H