polymer-overlay: only override transition target if null

Author: Yvonne Yip

polymer-animation/polymer-animation-group.html

@@ -73,6 +73,15 @@
         makeAnimation: function() {
           return new ANIMATION_GROUPS[this.type](this.childAnimations, this.timingProps);
         },
+        hasTarget: function() {
+          var ht = this.target !== null;
+          if (!ht) {
+            this.doOnChildren(function(c) {
+              ht = ht || c.hasTarget();
+            }.bind(this));
+          }
+          return ht;
+        },
         apply: function() {
           // Propagate target and duration to child animations first.
           this.durationChanged();

polymer-animation/polymer-animation.html

@@ -188,6 +188,9 @@
             this.player.source = null;
           }
         },
+        hasTarget: function() {
+          return this.target !== null;
+        },
         apply: function() {
           this.animation = null;
           this.animation = this.makeAnimation();

polymer-overlay/polymer-overlay.html

@@ -272,19 +272,20 @@
           this.target.style.top = this.target.style.left = null;
         },
         get transition() {
-          return (this.transitions && !Array.isArray(this.transitions)
+          return (!Array.isArray(this.transitions) && this.transitions
               || this.opened && this.transitions && this.transitions[0]
               || !this.opened && this.transitions && this.transitions[1]);
         },
         applyTransition: function() {
           var animation = typeof this.transition === 'string' ?
               document.createElement(this.transition) : this.transition;
           // FIXME: Apply a default duration.
-          console.log('animation', animation.duration, animation.type);
           if ((!animation.duration || animation.duration === 'auto') && !animation.type) {
             animation.duration = 0.3;
           }
-          animation.target = this.target;
+          if (!animation.hasTarget()) {
+            animation.target = this.target;
+          }
           // Make the overlay visible while the animation is running.
           var transition = new ParGroup([
             animation.makeAnimation(),