add detectChanges inside the stable block

Author: trshafer

src/lib/select/select.spec.ts

@@ -992,6 +992,7 @@ describe('MdSelect', () => {
         fixture.detectChanges();
 
         fixture.whenStable().then(() => {
+          fixture.detectChanges();
           const triggerLeft = trigger.getBoundingClientRect().left;
           const firstOptionLeft =
               document.querySelector('.cdk-overlay-pane md-option').getBoundingClientRect().left;
@@ -1011,6 +1012,7 @@ describe('MdSelect', () => {
         fixture.detectChanges();
 
         fixture.whenStable().then(() => {
+          fixture.detectChanges();
           const triggerRight = trigger.getBoundingClientRect().right;
           const firstOptionRight =
               document.querySelector('.cdk-overlay-pane md-option').getBoundingClientRect().right;