Mark Number and String as strict functions

src/bootstrapper.cc

 // Copyright 2014 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 "src/bootstrapper.h"
 
 #include "src/accessors.h"
 #include "src/api-natives.h"
 #include "src/base/ieee754.h"
 #include "src/code-stubs.h"
@@ skipping 1576 matching lines @@
   }
 
   {  // --- N u m b e r ---
     Handle<JSFunction> number_fun = InstallFunction(
         global, "Number", JS_VALUE_TYPE, JSValue::kSize,
         isolate->initial_object_prototype(), Builtins::kNumberConstructor);
     number_fun->shared()->DontAdaptArguments();
     number_fun->shared()->SetConstructStub(
         *isolate->builtins()->NumberConstructor_ConstructStub());
     number_fun->shared()->set_length(1);
+    // https://tc39.github.io/ecma262/#sec-built-in-function-objects says
+    // that "Built-in functions that are ECMAScript function objects must
+    // be strict functions".
+    number_fun->shared()->set_language_mode(STRICT);
     InstallWithIntrinsicDefaultProto(isolate, number_fun,
                                      Context::NUMBER_FUNCTION_INDEX);
 
     // Create the %NumberPrototype%
     Handle<JSValue> prototype =
         Handle<JSValue>::cast(factory->NewJSObject(number_fun, TENURED));
     prototype->set_value(Smi::kZero);
     JSFunction::SetPrototype(number_fun, prototype);
 
     // Install the "constructor" property on the {prototype}.
@@ skipping 125 matching lines @@
   }
 
   {  // --- S t r i n g ---
     Handle<JSFunction> string_fun = InstallFunction(
         global, "String", JS_VALUE_TYPE, JSValue::kSize,
         isolate->initial_object_prototype(), Builtins::kStringConstructor);
     string_fun->shared()->SetConstructStub(
         *isolate->builtins()->StringConstructor_ConstructStub());
     string_fun->shared()->DontAdaptArguments();
     string_fun->shared()->set_length(1);
+    // https://tc39.github.io/ecma262/#sec-built-in-function-objects says
+    // that "Built-in functions that are ECMAScript function objects must
+    // be strict functions".
+    string_fun->shared()->set_language_mode(STRICT);
     InstallWithIntrinsicDefaultProto(isolate, string_fun,
                                      Context::STRING_FUNCTION_INDEX);
 
     Handle<Map> string_map =
         Handle<Map>(native_context()->string_function()->initial_map());
     string_map->set_elements_kind(FAST_STRING_WRAPPER_ELEMENTS);
     Map::EnsureDescriptorSlack(string_map, 1);
 
     PropertyAttributes attribs = static_cast<PropertyAttributes>(
         DONT_ENUM | DONT_DELETE | READ_ONLY);
@@ skipping 3519 matching lines @@
 }
 
 
 // Called when the top-level V8 mutex is destroyed.
 void Bootstrapper::FreeThreadResources() {
   DCHECK(!IsActive());
 }
 
 }  // namespace internal
 }  // namespace v8