Drop unuseful `eval` call

If use CSP (without `unsafe-eval`), both `new Function` and `eval` will be forbidden, so `eval` part is just dead code.

The only possibility `eval` part would run was `new Function('return this')()` return a falsy value, but it never possible as the spec (Is there any old engine violate this? Never heard about that.)

This pr also add `new` keyword to make the code a little bit explicit.

buildin/global.js

@@ -7,7 +7,7 @@ g = (function() {
 
 try {
 	// This works if eval is allowed (see CSP)
-	g = g || Function("return this")() || (1, eval)("this");
+	g = g || new Function("return this")();
 } catch (e) {
 	// This works if the window reference is available
 	if (typeof window === "object") g = window;