fix: offset changes not being deteched in md-select

Author: crisbeto

src/lib/core/overlay/overlay-directives.ts

@@ -179,7 +179,7 @@ export class ConnectedOverlayDirective implements OnDestroy, OnChanges {
 
   ngOnChanges(changes: SimpleChanges) {
     if (changes['open']) {
-      changes['open'].currentValue ? this._attachOverlay() : this._detachOverlay();
+      this.open ? this._attachOverlay() : this._detachOverlay();
     }
   }
 

src/lib/select/select.ts

@@ -748,6 +748,10 @@ export class MdSelect implements AfterContentInit, OnDestroy, OnInit, ControlVal
     }
 
     this._checkOverlayWithinViewport(maxScroll);
+
+    // Change detection needs to be triggered in order for
+    // the overlay's position to get updated in time.
+    this._changeDetectorRef.detectChanges();
   }
 
   /**