add instance methods in the same class to localFieldStep

Author: erik-krogh

javascript/ql/src/semmle/javascript/dataflow/DataFlow.qll

@@ -1545,7 +1545,9 @@ module DataFlow {
    */
   predicate localFieldStep(DataFlow::Node pred, DataFlow::Node succ) {
     exists(ClassNode cls, string prop |
-      pred = cls.getAReceiverNode().getAPropertyWrite(prop).getRhs() and
+      pred = cls.getAReceiverNode().getAPropertyWrite(prop).getRhs() or
+      pred = cls.getInstanceMethod(prop)
+    |
       succ = cls.getAReceiverNode().getAPropertyRead(prop)
     )
   }

javascript/ql/test/library-tests/TypeTracking/class.js

@@ -0,0 +1,7 @@
+class Foo {
+    foo() {} // name: foo
+
+    bar() {
+        this.foo; // track: foo
+    }
+}