Add paper-menu-button and its dependencies to third_party/polymer

third_party/polymer/v1_0/components-chromium/iron-behaviors/iron-button-state-extracted.js

Index: third_party/polymer/v1_0/components-chromium/iron-behaviors/iron-button-state-extracted.js
diff --git a/third_party/polymer/v1_0/components-chromium/iron-behaviors/iron-button-state-extracted.js b/third_party/polymer/v1_0/components-chromium/iron-behaviors/iron-button-state-extracted.js
index a6516eb8ddaa5e77c0bf1d80d943d2837c6ffde3..f9b7f99b5355b26d0e6606fe3b1dfe80c650061a 100644
--- a/third_party/polymer/v1_0/components-chromium/iron-behaviors/iron-button-state-extracted.js
+++ b/third_party/polymer/v1_0/components-chromium/iron-behaviors/iron-button-state-extracted.js
@@ -77,6 +77,8 @@
       'space:keyup': '_spaceKeyUpHandler',
     },
 
+    _mouseEventRe: /^mouse/,
+
     _tapHandler: function() {
       if (this.toggles) {
        // a tap is needed to toggle the active state
@@ -97,7 +99,33 @@
       this.fire('change');
     },
 
-    _downHandler: function() {
+    _eventSourceIsPrimaryInput: function(event) {
+      event = event.detail.sourceEvent || event;
+
+      // Always true for non-mouse events....
+      if (!this._mouseEventRe.test(event.type)) {
+        return true;
+      }
+
+      // http://developer.mozilla.org/en-US/docs/Web/API/MouseEvent/buttons
+      if ('buttons' in event) {
+        return event.buttons === 1;
+      }
+
+      // http://developer.mozilla.org/en-US/docs/Web/API/MouseEvent/which
+      if (typeof event.which === 'number') {
+        return event.which < 2;
+      }
+
+      // http://developer.mozilla.org/en-US/docs/Web/API/MouseEvent/button
+      return event.button < 1;
+    },
+
+    _downHandler: function(event) {
+      if (!this._eventSourceIsPrimaryInput(event)) {
+        return;
+      }
+
       this._setPointerDown(true);
       this._setPressed(true);
       this._setReceivedFocusFromKeyboard(false);