Roll Polymer from 1.5.0 -> 1.6.0 to pick up native CSS custom props

third_party/polymer/v1_0/components-chromium/iron-fit-behavior/iron-fit-behavior-extracted.js

 /**
 `Polymer.IronFitBehavior` fits an element in another element using `max-height` and `max-width`, and
 optionally centers it in the window or another element.
 
 The element will only be sized and/or positioned if it has not already been sized and/or positioned
 by CSS.
 
 CSS properties               | Action
 -----------------------------|-------------------------------------------
 `position` set               | Element is not centered horizontally or vertically
@@ skipping 204 matching lines @@
         } else {
           this.fit();
         }
       }
     },
 
     /**
      * Positions and fits the element into the `fitInto` element.
      */
     fit: function() {
-      this._discoverInfo();
       this.position();
       this.constrain();
       this.center();
     },
 
     /**
      * Memoize information needed to position and size the target element.
      * @suppress {deprecated}
      */
     _discoverInfo: function() {
@@ skipping 81 matching lines @@
     },
 
     /**
      * Positions the element according to `horizontalAlign, verticalAlign`.
      */
     position: function() {
       if (!this.horizontalAlign && !this.verticalAlign) {
         // needs to be centered, and it is done after constrain.
         return;
       }
+      this._discoverInfo();
 
       this.style.position = 'fixed';
       // Need border-box for margin/padding.
       this.sizingTarget.style.boxSizing = 'border-box';
       // Set to 0, 0 in order to discover any offset caused by parent stacking contexts.
       this.style.left = '0px';
       this.style.top = '0px';
 
       var rect = this.getBoundingClientRect();
       var positionRect = this.__getNormalizedRect(this.positionTarget);
@@ skipping 40 matching lines @@
     },
 
     /**
      * Constrains the size of the element to `fitInto` by setting `max-height`
      * and/or `max-width`.
      */
     constrain: function() {
       if (this.horizontalAlign || this.verticalAlign) {
         return;
       }
+      this._discoverInfo();
+
       var info = this._fitInfo;
       // position at (0px, 0px) if not already positioned, so we can measure the natural size.
       if (!info.positionedBy.vertically) {
         this.style.position = 'fixed';
         this.style.top = '0px';
       }
       if (!info.positionedBy.horizontally) {
         this.style.position = 'fixed';
         this.style.left = '0px';
       }
@@ skipping 34 matching lines @@
     },
 
     /**
      * Centers horizontally and vertically if not already positioned. This also sets
      * `position:fixed`.
      */
     center: function() {
       if (this.horizontalAlign || this.verticalAlign) {
         return;
       }
+      this._discoverInfo();
+
       var positionedBy = this._fitInfo.positionedBy;
       if (positionedBy.vertically && positionedBy.horizontally) {
         // Already positioned.
         return;
       }
       // Need position:fixed to center
       this.style.position = 'fixed';
       // Take into account the offset caused by parents that create stacking
       // contexts (e.g. with transform: translate3d). Translate to 0,0 and
       // measure the bounding rect.
@@ skipping 120 matching lines @@
         // ones overlapping vertically.
         if (position.croppedArea === 0 && alignOk) {
           break;
         }
       }
 
       return position;
     }
 
   };