LibJS: Spec-compliant equality comparisons

The ECMAScript spec defines multiple equality operations which are used
all over the spec; this patch introduces them. Of course, the two
primary equality operations are AbtractEquals ('==') and StrictEquals
('==='), which have been renamed to 'abstract_eq' and 'strict_eq' in
this patch.

In support of the two operations mentioned above, the following have
also been added: SameValue, SameValueZero, and SameValueNonNumeric.
These are important to have, because they are used elsewhere in the spec
aside from the two primary equality comparisons.

Libraries/LibJS/Tests/switch-basic.js

@@ -1,4 +1,8 @@
+load("test-common.js");
+
 switch (1 + 2) {
+case '3':
+    assertNotReached();
 case 3:
     console.log("PASS");
     break;