fix(ripple): remove array.find() and enhance foundation code

- IE11 doesn't support array.prototype.find() so manually code loop
- no need to override existing activation - just allow touch to re-activate

Fixes #1328

packages/mdc-ripple/foundation.js

@@ -243,14 +243,12 @@ class MDCRippleFoundation extends MDCFoundation {
     }
 
     const {activationState_: activationState} = this;
-    if (activationState.isActivated) {
-      // Even when using touch, the effect can be activated by a
-      // 'mousedown'. But if the finger slides off, then there is
-      // no 'mouseup'. So we overwrite the event with 'touchstart',
-      // ifand when one occurs.
-      if (e.type === 'touchstart' && e.type !== activationState.activationEvent.type) {
-        activationState.activationEvent = e;
-      }
+    // We don't want to re-activate the ripple if it is already active -
+    // UNLESS there is a touch event - because even though 'mousedown' or 'pointerdown' will
+    // fire on a touch event, 'mouseup' or 'pointerup' will not fire if the finger moves off of the element
+    // before being removed, so we need the 'touchend' to be able to deactivate the
+    // state triggered by 'touchstart'.
+    if (activationState.isActivated && !(e.type === 'touchstart' && e.type !== activationState.activationEvent.type)) {
       return;
     }
 

packages/mdc-ripple/index.js

@@ -67,26 +67,28 @@ class MDCRipple extends MDCComponent {
       registerInteractionHandler: (evtType, handler) => {
         // If this is an 'up event' (the event name exists in the UP_EVENTS array),
         // add the listener at the window level. Otherwise, add it to the element.
-        if (!UP_EVENTS.find( (type) => {
+        // NOTE: IE11 precludes us from using Array.prototype.find
+        for (let i = 0, type; (type = UP_EVENTS[i]); i ++) {
           if ( type === evtType) {
             window.addEventListener(evtType, handler, util.applyPassive());
-            return true;
+            return;
           }
-        })) {
-          instance.root_.addEventListener(evtType, handler, util.applyPassive());
         }
+
+        instance.root_.addEventListener(evtType, handler, util.applyPassive());
       },
       deregisterInteractionHandler: (evtType, handler) => {
         // If this is an 'up event' (the event name exists in the UP_EVENTS array),
         // remove the listener from the window level. Otherwise, remove it from the element.
-        if (!UP_EVENTS.find( (type) => {
+        // NOTE: IE11 precludes us from using Array.prototype.find
+        for (let i = 0, type; (type = UP_EVENTS[i]); i ++) {
           if ( type === evtType) {
             window.removeEventListener(evtType, handler, util.applyPassive());
-            return true;
+            return;
           }
-        })) {
-          instance.root_.removeEventListener(evtType, handler, util.applyPassive());
         }
+
+        instance.root_.removeEventListener(evtType, handler, util.applyPassive());
       },
       registerResizeHandler: (handler) => window.addEventListener('resize', handler),
       deregisterResizeHandler: (handler) => window.removeEventListener('resize', handler),