Use StrictModeFlag in preparser and preparse data.

src/parser.cc

Index: src/parser.cc
diff --git a/src/parser.cc b/src/parser.cc
index 3c6c4ba1e2ced0c5cac9b22805c9ebdfba5a8049..37204c9a018e9aa8d6010e8645717f314f957ab2 100644
--- a/src/parser.cc
+++ b/src/parser.cc
@@ -4006,7 +4006,7 @@ FunctionLiteral* Parser::ParseFunctionLiteral(Handle<String> function_name,
         scanner().SeekForward(scope->end_position() - 1);
         materialized_literal_count = entry.literal_count();
         expected_property_count = entry.property_count();
-        if (entry.strict_mode()) top_scope_->SetStrictModeFlag(kStrictMode);
+        top_scope_->SetStrictModeFlag(entry.strict_mode_flag());
         only_simple_this_property_assignments = false;
         this_property_assignments = isolate()->factory()->empty_fixed_array();
         Expect(Token::RBRACE, CHECK_OK);