Move ParseYieldExpression to ParserBase.

src/preparser.cc

Index: src/preparser.cc
diff --git a/src/preparser.cc b/src/preparser.cc
index 4bb813711e06244d2f520c40a8f440a448108912..d6acac0cbb86875675a62adc92107751fa5174b1 100644
--- a/src/preparser.cc
+++ b/src/preparser.cc
@@ -142,11 +142,6 @@ PreParserExpression PreParserTraits::ParseFunctionLiteral(
 }
 
 
-PreParserExpression PreParserTraits::ParseYieldExpression(bool* ok) {
-  return pre_parser_->ParseYieldExpression(ok);
-}
-
-
 PreParserExpression PreParserTraits::ParseConditionalExpression(bool accept_IN,
                                                                 bool* ok) {
   return pre_parser_->ParseConditionalExpression(accept_IN, ok);
@@ -845,19 +840,6 @@ PreParser::Statement PreParser::ParseDebuggerStatement(bool* ok) {
 
 
 // Precedence = 3
-PreParser::Expression PreParser::ParseYieldExpression(bool* ok) {
-  // YieldExpression ::
-  //   'yield' '*'? AssignmentExpression
-  Consume(Token::YIELD);
-  Check(Token::MUL);
-
-  ParseAssignmentExpression(false, CHECK_OK);
-
-  return Expression::Default();
-}
-
-
-// Precedence = 3
 PreParser::Expression PreParser::ParseConditionalExpression(bool accept_IN,
                                                             bool* ok) {
   // ConditionalExpression ::