[parsing] Make FuncNameInferrer handle `extends` clauses properly

Bug: v8:7069
Change-Id: I878ea42207013a76de859c96f3cb5e2d93aa7927
Reviewed-on: https://chromium-review.googlesource.com/803908Reviewed-by: Marja Hölttä <marja@chromium.org>
Reviewed-by: Sathya Gunasekaran (ooo until 12/12) <gsathya@chromium.org>
Commit-Queue: Adam Klein <adamk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#50008}

src/parsing/parser-base.h

@@ -4470,6 +4470,7 @@ typename ParserBase<Impl>::ExpressionT ParserBase<Impl>::ParseClassLiteral(
 
   scope()->set_start_position(scanner()->location().end_pos);
   if (Check(Token::EXTENDS)) {
+    FuncNameInferrer::State fni_state(fni_);
     ExpressionClassifier extends_classifier(this);
     class_info.extends = ParseLeftHandSideExpression(CHECK_OK);
     impl()->RewriteNonPattern(CHECK_OK);

test/cctest/test-func-name-inference.cc

@@ -555,3 +555,19 @@ TEST(ReturnAnonymousFunction) {
   script->Run(CcTest::isolate()->GetCurrentContext()).ToLocalChecked();
   CheckFunctionName(script, "return 2012", "");
 }
+
+TEST(IgnoreExtendsClause) {
+  CcTest::InitializeVM();
+  v8::HandleScope scope(CcTest::isolate());
+
+  v8::Local<v8::Script> script =
+      Compile(CcTest::isolate(),
+              "(function() {\n"
+              "  var foo = {};\n"
+              "  foo.C = class {}\n"
+              "  class D extends foo.C {}\n"
+              "  foo.bar = function() { return 1; };\n"
+              "})()");
+  script->Run(CcTest::isolate()->GetCurrentContext()).ToLocalChecked();
+  CheckFunctionName(script, "return 1", "foo.bar");
+}