fix(ripple): use contentParent scroll offset

Closes #416.

Author: ajoslin

src/components/animate/inkCssRipple.js

@@ -63,6 +63,7 @@ function InkRippleService($window, $$rAF, $mdEffects, $timeout, $mdUtil) {
   function attach(element, options) {
     // Parent element with noink attr? Abort.
     if (element.controller('noink')) return angular.noop;
+    var contentParent = element.controller('mdContent');
 
     options = angular.extend({
       mousedown: true,
@@ -125,6 +126,10 @@ function InkRippleService($window, $$rAF, $mdEffects, $timeout, $mdUtil) {
         top -= elementRect.top;
       }
 
+      if (contentParent) {
+        top += contentParent.$element.prop('scrollTop');
+      }
+
       var css = {
         'background-color': $window.getComputedStyle(rippleEl[0]).color || 
           $window.getComputedStyle(node).color,