Remove extra if statement.

Author: crisbeto

src/lib/dialog/dialog.ts

@@ -64,14 +64,12 @@ export class MdDialog {
   closeAll(): void {
     let i = this._openDialogs.length;
 
-    if (i > 0) {
-      while (i--) {
-        // The `_openDialogs` property isn't updated after close until the rxjs subscription
-        // runs on the next microtask, in addition to modifying the array as we're going
-        // through it. We loop through all of them and call close without assuming that
-        // they'll be removed from the list instantaneously.
-        this._openDialogs[i].close();
-      }
+    while (i--) {
+      // The `_openDialogs` property isn't updated after close until the rxjs subscription
+      // runs on the next microtask, in addition to modifying the array as we're going
+      // through it. We loop through all of them and call close without assuming that
+      // they'll be removed from the list instantaneously.
+      this._openDialogs[i].close();
     }
   }