Allow configuring cancelling synthetic click behavior (#5536)

lib/utils/gestures.html

@@ -226,6 +226,9 @@
   }
 
   function ignoreMouse(e) {
+    if (!Polymer.cancelSyntheticClickEvents) {
+      return;
+    }
     if (!POINTERSTATE.mouse.mouseIgnoreJob) {
       setupTeardownMouseCanceller(true);
     }
@@ -335,9 +338,11 @@
     stateObj.upfn = null;
   }
 
-  // use a document-wide touchend listener to start the ghost-click prevention mechanism
-  // Use passive event listeners, if supported, to not affect scrolling performance
-  document.addEventListener('touchend', ignoreMouse, SUPPORTS_PASSIVE ? {passive: true} : false);
+  if (Polymer.cancelSyntheticClickEvents) {
+    // use a document-wide touchend listener to start the ghost-click prevention mechanism
+    // Use passive event listeners, if supported, to not affect scrolling performance
+    document.addEventListener('touchend', ignoreMouse, SUPPORTS_PASSIVE ? {passive: true} : false);
+  }
 
   /**
    * Module for adding listeners to a node for the following normalized

lib/utils/settings.html

@@ -122,5 +122,21 @@
   Polymer.setLegacyOptimizations = function(useLegacyOptimizations) {
     Polymer.legacyOptimizations = useLegacyOptimizations;
   };
+
+  Polymer.cancelSyntheticClickEvents = typeof Polymer.cancelSyntheticClickEvents === 'boolean'
+    ? Polymer.cancelSyntheticClickEvents : true;
+
+  /**
+  * Sets `setCancelSyntheticEvents` globally for all elements to cancel synthetic click events
+  * fired by older mobile browsers. Modern browsers no longer fire synthetic click events, and
+  * the cancellation behavior can interfere when programmatically clicking on elements.
+  *
+  * @param {boolean} useCancelSyntheticClickEvents enable or disable cancelling synthetic
+  * events
+  * @return {void}
+  */
+  Polymer.setCancelSyntheticClickEvents = function(useCancelSyntheticClickEvents) {
+    Polymer.cancelSyntheticClickEvents = useCancelSyntheticClickEvents;
+  };
 })();
 </script>