update elements and fix some bugs

lib/src/paper-checkbox/paper-checkbox.html

 <!--
 @license
 Copyright (c) 2015 The Polymer Project Authors. All rights reserved.
 This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
 The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
 The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
 Code distributed by Google as part of the polymer project is also
 subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
 -->
 
 <link rel="import" href="../polymer/polymer.html">
 <link rel="import" href="../paper-ripple/paper-ripple.html">
 <link rel="import" href="../paper-styles/default-theme.html">
 <link rel="import" href="../paper-styles/color.html">
-<link rel="import" href="../paper-behaviors/paper-inky-focus-behavior.html">
-<link rel="import" href="../iron-checked-element-behavior/iron-checked-element-behavior.html">
+<link rel="import" href="../paper-behaviors/paper-checked-element-behavior.html">
+
 <!--
+Material design: [Checkbox](https://www.google.com/design/spec/components/selection-controls.html#selection-controls-checkbox)
 
 `paper-checkbox` is a button that can be either checked or unchecked.  User
 can tap the checkbox to check or uncheck it.  Usually you use checkboxes
 to allow user to select multiple options from a set.  If you have a single
 ON/OFF option, avoid using a single checkbox and use `paper-toggle-button`
 instead.
 
 Example:
 
     <paper-checkbox>label</paper-checkbox>
 
     <paper-checkbox checked> label</paper-checkbox>
 
 ### Styling
 
 The following custom properties and mixins are available for styling:
 
 Custom property | Description | Default
 ----------------|-------------|----------
 `--paper-checkbox-unchecked-background-color` | Checkbox background color when the input is not checked | `transparent`
 `--paper-checkbox-unchecked-color` | Checkbox border color when the input is not checked | `--primary-text-color`
 `--paper-checkbox-unchecked-ink-color` | Selected/focus ripple color when the input is not checked | `--primary-text-color`
 `--paper-checkbox-checked-color` | Checkbox color when the input is checked | `--default-primary-color`
 `--paper-checkbox-checked-ink-color` | Selected/focus ripple color when the input is checked | `--default-primary-color`
 `--paper-checkbox-checkmark-color` | Checkmark color | `white`
 `--paper-checkbox-label-color` | Label color | `--primary-text-color`
+`--paper-checkbox-label-spacing` | Spacing between the label and the checkbox | `8px`
 `--paper-checkbox-error-color` | Checkbox color when invalid | `--google-red-500`
 
 @demo demo/index.html
 -->
 
 <dom-module id="paper-checkbox">
-  <template>
+  <template strip-whitespace>
     <style>
       :host {
         display: inline-block;
         white-space: nowrap;
       }
 
       :host(:focus) {
         outline: none;
       }
 
       .hidden {
         display: none;
       }
 
       #checkboxContainer {
         display: inline-block;
         position: relative;
         width: 18px;
         height: 18px;
         cursor: pointer;
         -webkit-transform: translateZ(0);
         transform: translateZ(0);
         vertical-align: middle;
         background-color: var(--paper-checkbox-unchecked-background-color, transparent);
       }
 
-      :host #ink {
+      #ink {
         position: absolute;
         top: -15px;
         left: -15px;
         width: 48px;
         height: 48px;
         color: var(--paper-checkbox-unchecked-ink-color, --primary-text-color);
         opacity: 0.6;
         pointer-events: none;
       }
 
-      :host #ink[checked] {
+      :host-context([dir="rtl"]) #ink {
+        right: -15px;
+        left: auto;
+      }
+
+      #ink[checked] {
         color: var(--paper-checkbox-checked-ink-color, --default-primary-color);
       }
 
-      :host #checkbox {
+      #checkbox {
         position: relative;
         box-sizing: border-box;
         height: 100%;
         border: solid 2px;
         border-color: var(--paper-checkbox-unchecked-color, --primary-text-color);
         border-radius: 2px;
         pointer-events: none;
         -webkit-transition: background-color 140ms, border-color 140ms;
         transition: background-color 140ms, border-color 140ms;
       }
@@ skipping 27 matching lines @@
           height: 0px;
         }
         100% {
           top: -1px;
           left: 4px;
           width: 5px;
           height: 10px;
         }
       }
 
-      :host #checkbox.checked {
+      #checkbox.checked {
         background-color: var(--paper-checkbox-checked-color, --default-primary-color);
         border-color: var(--paper-checkbox-checked-color, --default-primary-color);
       }
 
-      :host #checkmark {
+      #checkmark {
         -webkit-transform: rotate(45deg);
         transform: rotate(45deg);
         position: absolute;
         top: -1px;
         left: 4px;
         width: 5px;
         height: 10px;
         border-style: solid;
         border-top: none;
         border-left: none;
         border-right-width: 2px;
         border-bottom-width: 2px;
         border-color: var(--paper-checkbox-checkmark-color, white);
       }
 
       /* label */
       #checkboxLabel {
         position: relative;
         display: inline-block;
         vertical-align: middle;
-        padding-left: 8px;
+        padding-left: var(--paper-checkbox-label-spacing, 8px);
         white-space: normal;
         pointer-events: none;
         color: var(--paper-checkbox-label-color, --primary-text-color);
       }
 
+      :host-context([dir="rtl"]) #checkboxLabel {
+        padding-right: var(--paper-checkbox-label-spacing, 8px);
+        padding-left: 0;
+      }
+
       #checkboxLabel[hidden] {
         display: none;
       }
 
       /* disabled state */
       :host([disabled]) {
         pointer-events: none;
       }
 
       :host([disabled]) #checkbox {
@@ skipping 10 matching lines @@
         opacity: 0.65;
       }
 
       /* invalid state */
       #checkbox.invalid:not(.checked) {
         border-color: var(--paper-checkbox-error-color, --google-red-500);
       }
     </style>
 
     <div id="checkboxContainer">
-      <paper-ripple id="ink" class="circle" center checked$="[[checked]]"></paper-ripple>
       <div id="checkbox" class$="[[_computeCheckboxClass(checked, invalid)]]">
         <div id="checkmark" class$="[[_computeCheckmarkClass(checked)]]"></div>
       </div>
     </div>
 
     <div id="checkboxLabel"><content></content></div>
   </template>
 
   <script>
     Polymer({
       is: 'paper-checkbox',
 
       behaviors: [
-        Polymer.PaperInkyFocusBehavior,
-        Polymer.IronCheckedElementBehavior
+        Polymer.PaperCheckedElementBehavior
       ],
 
       hostAttributes: {
         role: 'checkbox',
         'aria-checked': false,
         tabindex: 0
       },
 
       properties: {
         /**
          * Fired when the checked state changes due to user interaction.
          *
          * @event change
          */
 
         /**
          * Fired when the checked state changes.
          *
          * @event iron-change
          */
         ariaActiveAttribute: {
           type: String,
           value: 'aria-checked'
         }
       },
 
-      attached: function() {
-        this._isReady = true;
-
-        // Don't stomp over a user-set aria-label.
-        if (!this.getAttribute('aria-label')) {
-          this.updateAriaLabel();
-        }
-      },
-
-      /**
-       * Update the checkbox aria-label. This is a temporary workaround not
-       * being able to observe changes in <content>
-       * (see: https://github.com/Polymer/polymer/issues/1773)
-       *
-       * Call this if you manually change the contents of the checkbox
-       * and want the aria-label to match the new contents.
-       */
-      updateAriaLabel: function() {
-        this.setAttribute('aria-label', Polymer.dom(this).textContent.trim());
-      },
-
-      // button-behavior hook
-      _buttonStateChanged: function() {
-        if (this.disabled) {
-          return;
-        }
-        if (this._isReady) {
-          this.checked = this.active;
-        }
-      },
-
       _computeCheckboxClass: function(checked, invalid) {
         var className = '';
         if (checked) {
           className += 'checked ';
         }
         if (invalid) {
           className += 'invalid';
         }
         return className;
       },
 
       _computeCheckmarkClass: function(checked) {
         return checked ? '' : 'hidden';
+      },
+
+      // create ripple inside the checkboxContainer
+      _createRipple: function() {
+        this._rippleContainer = this.$.checkboxContainer;
+        return Polymer.PaperInkyFocusBehaviorImpl._createRipple.call(this);
       }
+
     });
   </script>
 </dom-module>