Expose sizing and position properties on iron-image

paper-card.html

@@ -128,7 +128,7 @@
     </style>
 
     <div class="header">
-      <iron-image hidden$="[[!image]]" src="[[image]]" preload$="[[preloadImage]]" fade$="[[fadeImage]]"></iron-image>
+      <iron-image hidden$="[[!image]]" src="[[image]]" preload$="[[preloadImage]]" fade$="[[fadeImage]]" sizing$="[[sizingImage]]" position$="[[positionImage]]"></iron-image>
       <div hidden$="[[!heading]]" class$="[[_computeHeadingClass(image)]]">[[heading]]</div>
     </div>
 
@@ -175,6 +175,26 @@
           value: false
         },
 
+        /**
+         * Binds to `iron-image` sizing property. Valid values are contain
+         * (full aspect ratio of the image is contained within the element and letterboxed)
+         * or cover (image is cropped in order to fully cover the bounds of the element),
+         * or null (default: image takes natural size).
+         */
+        sizingImage: {
+          type: String,
+          value: null
+        },
+
+        /**
+         * Binds to `iron-image` position property. When a sizing option is used (cover or contain),
+         * this determines how the image is aligned within the element bounds.
+         */
+        positionImage: {
+          type: String,
+          value: 'center'
+        },
+
         /**
          * The z-depth of the card, from 0-5.
          */