fix(select): Should float asterisk if no placeholder (#1784)

reference: #1766

Author: trimox

demos/src/app/components/select-demo/examples.html

@@ -143,7 +143,7 @@ <h3 class="demo-content__headline">Custom Enhanced</h3>
 <div class="demo-content">
   <h3 class="demo-content__headline">Lazy Load</h3>
   <form [formGroup]="lazyLoadForm" #formDirectiveLazy="ngForm">
-    <mdc-select outlined formControlName="lazySelect" [helperText]="lazyHelper">
+    <mdc-select outlined formControlName="lazySelect" [helperText]="lazyHelper" class="demo-enhanced-width">
       <option *ngFor="let food of lazyFoods" [value]="food.value" [disabled]="food.disabled">{{food.viewValue}}</option>
     </mdc-select>
     <mdc-helper-text #lazyHelper validation>
@@ -245,4 +245,4 @@ <h3 class="demo-content__headline">Select with FormControl</h3>
   <p>Value: {{ foodForm.value | json }}</p>
 
   <example-viewer [example]="exampleReactive"></example-viewer>
-</div>
+</div>

packages/select/select.ts

@@ -693,7 +693,8 @@ export class MdcSelect extends _MdcSelectMixinBase implements AfterViewInit, DoC
   }
 
   private _hasFloatingLabel(): boolean {
-    return this.placeholder && this.floatLabel && (this._floatingLabel || this._notchedOutline) ? true : false;
+    return (this.placeholder && this.floatLabel) || this._required
+      && (this._floatingLabel || this._notchedOutline) ? true : false;
   }
 
   private _getFloatingLabel(): MdcFloatingLabel {