LibJS: Implement Infinity

Author: https://github.com/linusg
Commit: 543c6e00db
Pull-request: https://github.com/SerenityOS/serenity/pull/1584

Libraries/LibJS/Tests/Infinity-basic.js

@@ -0,0 +1,27 @@
+function assert(x) { if (!x) throw 1; }
+
+try {
+    assert(Infinity + "" === "Infinity");
+    assert(-Infinity + "" === "-Infinity");
+    assert(Infinity === Infinity);
+    assert(Infinity - 1 === Infinity);
+    assert(Infinity + 1 === Infinity);
+    assert(-Infinity === -Infinity);
+    assert(-Infinity - 1 === -Infinity);
+    assert(-Infinity + 1 === -Infinity);
+    assert(1 / Infinity === 0);
+    assert(1 / -Infinity === 0);
+    assert(1 / 0 === Infinity);
+    assert(-1 / 0 === -Infinity);
+    assert(-100 < Infinity);
+    assert(0 < Infinity);
+    assert(100 < Infinity);
+    assert(-Infinity < Infinity);
+    assert(-100 > -Infinity);
+    assert(0 > -Infinity);
+    assert(100 > -Infinity);
+    assert(Infinity > -Infinity);
+    console.log("PASS");
+} catch (e) {
+    console.log("FAIL: " + e);
+}