Add parsing for class declarations

src/parsing/preparser.cc

 // Copyright 2011 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.
 
 #include <cmath>
 
 #include "src/allocation.h"
 #include "src/base/logging.h"
 #include "src/conversions-inl.h"
 #include "src/conversions.h"
@@ skipping 1120 matching lines @@
   }
 
   LanguageMode class_language_mode = language_mode();
   Scope* scope = NewScope(scope_, BLOCK_SCOPE);
   BlockState block_state(&scope_, scope);
   scope_->SetLanguageMode(
       static_cast<LanguageMode>(class_language_mode | STRICT));
   // TODO(marja): Make PreParser use scope names too.
   // scope_->SetScopeName(name);
 
+  // Parse optional type parameters.
+  if (scope_->typed() && peek() == Token::LT) {  // Braces required here.
+    ParseTypeParameters(CHECK_OK);
+  }
+
+  // Parse optional extends clause.
   bool has_extends = Check(Token::EXTENDS);
   if (has_extends) {
     ExpressionClassifier classifier(this);
     ParseLeftHandSideExpression(&classifier, CHECK_OK);
     ValidateExpression(&classifier, CHECK_OK);
   }
 
+  // Parse optional implements clause.
+  if (scope_->typed() && CheckContextualKeyword(CStrVector("implements"))) {
+    do {
+      ParseTypeReference(CHECK_OK);
+    } while (Check(Token::COMMA));
+  }
+
   ClassLiteralChecker checker(this);
   bool has_seen_constructor = false;
 
   Expect(Token::LBRACE, CHECK_OK);
   while (peek() != Token::RBRACE) {
     if (Check(Token::SEMICOLON)) continue;
     const bool in_class = true;
     const bool is_static = false;
     bool is_computed_name = false;  // Classes do not care about computed
                                     // property names here.
@@ skipping 46 matching lines @@
     Expect(Token::RBRACE, CHECK_OK);
     return PreParserExpression::Default();
   }
 }
 
 #undef CHECK_OK
 
 
 }  // namespace internal
 }  // namespace v8