Remove invalid assertion in ecma_builtin_global_object_eval.

The removed assertion checked that `this` argument can't be equal to `undefined` in direct call to eval.
Actually, `this` can be not equal to `undefined` in case direct call to eval is performed from `with` block.

Related issue: #212

JerryScript-DCO-1.0-Signed-off-by: Ruben Ayrapetyan r.ayrapetyan@samsung.com

tests/jerry/regression-test-issue-212.js

@@ -0,0 +1,17 @@
+// Copyright 2015 Samsung Electronics Co., Ltd.
+// Copyright 2015 University of Szeged.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+with(0xB276)
+  eval("foo = true;");