Initial exploration and test case creation

Co-authored-by: RyanCavanaugh <6685088+RyanCavanaugh@users.noreply.github.com>

tests/cases/compiler/thisTypeComparison.ts

@@ -0,0 +1,17 @@
+// @strict: true
+
+class AA {
+    do1() {
+        const b = dd.getB();
+        if (this === b) {
+            console.log("this === b");
+        }
+    }
+}
+
+class BB extends AA {
+    getB(): BB { return this; }
+}
+
+let dd = new BB();
+dd.do1();