[runtime] Use strict mode map for the Proxy function

Bug: v8:6873
Change-Id: I1f544065dfec406bf3e4f16df38e80a1b1f7a173
Reviewed-on: https://chromium-review.googlesource.com/702281Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48337}

src/bootstrapper.cc

@@ -3304,7 +3304,7 @@ void Genesis::InitializeGlobal(Handle<JSGlobalObject> global_object,
     CreateJSProxyMaps();
 
     Handle<Map> proxy_function_map =
-        Map::Copy(isolate->sloppy_function_without_prototype_map(), "Proxy");
+        Map::Copy(isolate->strict_function_without_prototype_map(), "Proxy");
     proxy_function_map->set_is_constructor(true);
 
     Handle<String> name = factory->Proxy_string();

test/mjsunit/es6/proxies.js

@@ -49,6 +49,19 @@ function TestWithFunctionProxy(test, x, y, z) {
   test((handler) => { return new Proxy(() => {}, handler) }, x, y, z)
 }
 
+// ---------------------------------------------------------------------------
+// Test Proxy constructor properties
+
+(function TestProxyProperties() {
+  assertEquals(2, Proxy.length);
+  assertEquals(Function.__proto__, Proxy.__proto__);
+  assertEquals(null, Proxy.prototype);
+  assertEquals(undefined, Object.getOwnPropertyDescriptor(Proxy, "arguments"));
+  assertThrows(() => Proxy.arguments, TypeError);
+  assertEquals(undefined, Object.getOwnPropertyDescriptor(Proxy, "caller"));
+  assertThrows(() => Proxy.caller, TypeError);
+})();
+
 // ---------------------------------------------------------------------------
 // Getting property descriptors (Object.getOwnPropertyDescriptor).