fix(tooltip): moves tooltip to the $rootElement rather than body or m…

…d-content

src/components/tooltip/tooltip.js

@@ -33,7 +33,8 @@ angular
  * @param {string=} md-direction Which direction would you like the tooltip to go?  Supports left, right, top, and bottom.  Defaults to bottom.
  * @param {boolean=} md-autohide If present or provided with a boolean value, the tooltip will hide on mouse leave, regardless of focus
  */
-function MdTooltipDirective($timeout, $window, $$rAF, $document, $mdUtil, $mdTheming, $animate, $q) {
+function MdTooltipDirective($timeout, $window, $$rAF, $document, $mdUtil, $mdTheming, $rootElement,
+                            $animate, $q) {
 
   var TOOLTIP_SHOW_DELAY = 300;
   var TOOLTIP_WINDOW_EDGE_SPACE = 8;
@@ -111,13 +112,7 @@ function MdTooltipDirective($timeout, $window, $$rAF, $document, $mdUtil, $mdThe
     }
 
     function getNearestContentElement () {
-      var current = element.parent()[0];
-      // Look for the nearest parent md-content
-      while (current && current !== document.body) {
-        if (current.tagName && current.tagName.toLowerCase() == 'md-content') break;
-        current = current.parentNode;
-      }
-      return current;
+      return $rootElement;
     }
 
     function hasComputedStyleValue(key, value) {