LibJS: Fix broken parsing of !o.a

Unary expressions parsing now respects precedence and associativity of
operators. This patch also makes `typeof` left-associative which was
an oversight.

Thanks to Conrad for helping me work this out. :^)

Libraries/LibJS/Tests/parser-unary-associativity.js

@@ -0,0 +1,18 @@
+function assert(x) { if (!x) throw 1; }
+
+try {
+    var o = {};
+    o.a = 1;
+
+    assert(o.a === 1);
+    assert(!o.a === false);
+    assert(!o.a === !(o.a));
+    assert(~o.a === ~(o.a));
+
+    assert((typeof "x" === "string") === true);
+    assert(!(typeof "x" === "string") === false);
+
+    console.log("PASS");
+} catch (e) {
+    console.log("FAIL: " + e);
+}