LibJS: Parse while statements

Author: https://github.com/linusg
Commit: 038051d205
Pull-request: https://github.com/SerenityOS/serenity/pull/1906
Reviewed-by: https://github.com/alimpfard

Libraries/LibJS/Tests/while-basic.js

@@ -0,0 +1,21 @@
+load("test-common.js");
+
+try {
+    var number = 0;
+    while (number < 9) {
+        number++;
+    }
+    assert(number === 9);
+
+    number = 0;
+    while(number < 3) number++;
+    assert(number === 3);
+
+    while (false) {
+        assertNotReached();
+    }
+
+    console.log("PASS");
+} catch (e) {
+    console.log("FAIL: " + e);
+}