Make built-ins strict mode conforming, and support a --use-strict flag.

src/compiler.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 482 matching lines @@
 
   if (result.is_null()) {
     // No cache entry found. Do pre-parsing, if it makes sense, and compile
     // the script.
     // Building preparse data that is only used immediately after is only a
     // saving if we might skip building the AST for lazily compiled functions.
     // I.e., preparse data isn't relevant when the lazy flag is off, and
     // for small sources, odds are that there aren't many functions
     // that would be compiled lazily anyway, so we skip the preparse step
     // in that case too.
-    int flags = kNoParsingFlags;
-    if ((natives == NATIVES_CODE) || FLAG_allow_natives_syntax) {
-      flags |= kAllowNativesSyntax;
-    }
-    if (natives != NATIVES_CODE && FLAG_harmony_scoping) {
-      flags |= EXTENDED_MODE;
-    }
 
     // Create a script object describing the script to be compiled.
     Handle<Script> script = FACTORY->NewScript(source);
     if (natives == NATIVES_CODE) {
       script->set_type(Smi::FromInt(Script::TYPE_NATIVE));
     }
     if (!script_name.is_null()) {
       script->set_name(*script_name);
       script->set_line_offset(Smi::FromInt(line_offset));
       script->set_column_offset(Smi::FromInt(column_offset));
     }
 
     script->set_data(script_data.is_null() ? HEAP->undefined_value()
                                            : *script_data);
 
     // Compile the function and add it to the cache.
     CompilationInfo info(script);
     info.MarkAsGlobal();
     info.SetExtension(extension);
     info.SetPreParseData(pre_data);
+    if (FLAG_use_strict) info.SetLanguageMode(STRICT_MODE);
     result = MakeFunctionInfo(&info);
     if (extension == NULL && !result.is_null()) {
       compilation_cache->PutScript(source, result);
     }
   }
 
   if (result.is_null()) isolate->ReportPendingMessages();
   return result;
 }
 
@@ skipping 269 matching lines @@
     }
   }
 
   GDBJIT(AddCode(Handle<String>(shared->DebugName()),
                  Handle<Script>(info->script()),
                  Handle<Code>(info->code()),
                  info));
 }
 
 } }  // namespace v8::internal