LibJS: Remove Proxy() argument count check

Let's just treat missing arguments as undefined and throw with
'target/handler must be object' - this is more JavaScript-y.

Userland/Libraries/LibJS/Runtime/ErrorTypes.h

@@ -128,7 +128,6 @@
     M(ProxySetPrototypeOfNonExtensible, "Proxy handler's setPrototypeOf trap violates "                                                 \
                                         "invariant: the argument must match the prototype of the target if the "                        \
                                         "target is non-extensible")                                                                     \
-    M(ProxyTwoArguments, "Proxy constructor requires at least two arguments")                                                           \
     M(ReduceNoInitial, "Reduce of empty array with no initial value")                                                                   \
     M(ReferenceNullishDeleteProperty, "Cannot delete property '{}' of {}")                                                              \
     M(ReferenceNullishGetProperty, "Cannot get property '{}' of {}")                                                                    \

Userland/Libraries/LibJS/Runtime/ProxyConstructor.cpp

@@ -38,11 +38,6 @@ Value ProxyConstructor::call()
 Value ProxyConstructor::construct(Function&)
 {
     auto& vm = this->vm();
-    if (vm.argument_count() < 2) {
-        vm.throw_exception<TypeError>(global_object(), ErrorType::ProxyTwoArguments);
-        return {};
-    }
-
     auto target = vm.argument(0);
     auto handler = vm.argument(1);
 

Userland/Libraries/LibJS/Tests/builtins/Proxy/Proxy.js

@@ -7,11 +7,17 @@ test("constructs properly", () => {
 test("constructor argument count", () => {
     expect(() => {
         new Proxy();
-    }).toThrowWithMessage(TypeError, "Proxy constructor requires at least two arguments");
+    }).toThrowWithMessage(
+        TypeError,
+        "Expected target argument of Proxy constructor to be object, got undefined"
+    );
 
     expect(() => {
         new Proxy({});
-    }).toThrowWithMessage(TypeError, "Proxy constructor requires at least two arguments");
+    }).toThrowWithMessage(
+        TypeError,
+        "Expected handler argument of Proxy constructor to be object, got undefined"
+    );
 });
 
 test("constructor requires objects", () => {