fix getPrototypeOf behavior around foreign objects and activate tests

Author: wirthi

graal-js/src/com.oracle.truffle.js.test/src/com/oracle/truffle/js/test/interop/ForeignObjectPrototypeTest.java

@@ -131,9 +131,9 @@ public void testPrototype() {
         testPrototypeIntl("Array", ProxyArray.fromArray("fun", "with", "proxy", "array"));
         testPrototypeIntl("Date", Instant.now());
         testPrototypeIntl("Map", new TestTruffleHash());
-        // testPrototypeIntl("String", new TestTruffleString());
-        // testPrototypeIntl("Boolean", new TestTruffleBoolean());
-        // testPrototypeIntl("Number", new TestTruffleNumber());
+        testPrototypeIntl("String", new TestTruffleString());
+        testPrototypeIntl("Boolean", new TestTruffleBoolean());
+        testPrototypeIntl("Number", new TestTruffleNumber());
         testPrototypeIntl("Function", (ProxyExecutable) v -> true);
         testPrototypeIntl("Object", new Object());
     }

graal-js/src/com.oracle.truffle.js/src/com/oracle/truffle/js/builtins/ObjectFunctionBuiltins.java

@@ -299,23 +299,28 @@ public ObjectGetPrototypeOfNode(JSContext context, JSBuiltin builtin) {
         }
 
         @Specialization(guards = "!isJSObject(object)")
-        protected JSDynamicObject getPrototypeOfNonObject(Object object) {
+        protected JSDynamicObject getPrototypeOfNonObject(Object object,
+                        @Cached("createBinaryProfile()") ConditionProfile isForeignProfile) {
             if (getContext().getEcmaScriptVersion() < 6) {
                 if (JSRuntime.isJSPrimitive(object)) {
                     throw Errors.createTypeErrorNotAnObject(object);
                 } else {
                     return Null.instance;
                 }
             } else {
-                Object tobject = toObject(object);
-                if (JSDynamicObject.isJSDynamicObject(tobject)) {
-                    return JSObject.getPrototype((JSDynamicObject) tobject);
-                } else {
+                if (isForeignProfile.profile(JSRuntime.isForeignObject(object))) {
+                    if (InteropLibrary.getUncached(object).isNull(object)) {
+                        throw Errors.createTypeErrorNotAnObject(object);
+                    }
                     if (getContext().getContextOptions().hasForeignObjectPrototype()) {
-                        return getForeignObjectPrototype(tobject);
+                        return getForeignObjectPrototype(object);
                     } else {
                         return Null.instance;
                     }
+                } else {
+                    assert JSRuntime.isJSPrimitive(object);
+                    Object tobject = toObject(object);
+                    return JSObject.getPrototype((JSDynamicObject) tobject);
                 }
             }
         }