Limit entry points into the parser API.

src/parser.cc

Index: src/parser.cc
diff --git a/src/parser.cc b/src/parser.cc
index 05ae11e4291ae8c169d962dad7531b05cc0fc1bd..c77c17126fa442ef420eb2720b510a497a153ced 100644
--- a/src/parser.cc
+++ b/src/parser.cc
@@ -3170,8 +3170,7 @@ Expression* Parser::ParseUnaryExpression(bool* ok) {
       if (op == Token::NOT) {
         // Convert the literal to a boolean condition and negate it.
         bool condition = literal->BooleanValue();
-        Handle<Object> result(isolate()->heap()->ToBoolean(!condition),
-                              isolate());
+        Handle<Object> result = isolate()->factory()->ToBoolean(!condition);
         return factory()->NewLiteral(result);
       } else if (literal->IsNumber()) {
         // Compute some expressions involving only number literals.