[asm-cherry-pick] Associate LabelNodes with their corresponding label

Cherry-pick of
lrytz/scala@2458576

Author: lrytz

src/main/java/scala/tools/asm/tree/MethodNode.java

@@ -623,7 +623,7 @@ public void visitEnd() {
      */
     protected LabelNode getLabelNode(final Label l) {
         if (!(l.info instanceof LabelNode)) {
-            l.info = new LabelNode();
+            l.info = new LabelNode(l);
         }
         return (LabelNode) l.info;
     }