fix(tooltip): remove tooltip component after it's parent destroyed (#1470)

Fixes #1111

Author: gucheen

src/lib/tooltip/tooltip.spec.ts

@@ -50,6 +50,14 @@ describe('MdTooltip', () => {
       tooltipDirective._handleMouseLeave(null);
       expect(overlayContainerElement.textContent).toBe('');
     });
+
+    it('should be removed after parent destroyed', () => {
+      tooltipDirective._handleMouseEnter(null);
+      expect(tooltipDirective.visible).toBeTruthy();
+      fixture.destroy();
+      expect(overlayContainerElement.childNodes.length).toBe(0);
+      expect(overlayContainerElement.textContent).toBe('');
+    });
   });
 });
 

src/lib/tooltip/tooltip.ts

@@ -68,6 +68,15 @@ export class MdTooltip {
     this._createOverlay();
   }
 
+  /**
+   * Remove overlay after tooltip's parent has been destroyed
+   */
+  ngOnDestroy() {
+    this.visible = false;
+    this._overlayRef.dispose();
+    this._overlayRef = null;
+  }
+
   /**
    * Create the overlay config and position strategy
    */