add more room for arrow, account for margin

Author: andrewseguin

src/lib/select/select.scss

@@ -24,7 +24,6 @@ $mat-select-panel-max-height: 256px !default;
   position: relative;
 
   [aria-disabled='true'] & {
-    background-position: 0 bottom;
     cursor: default;
     user-select: none;
   }
@@ -77,7 +76,7 @@ $mat-select-panel-max-height: 256px !default;
 
 .mat-select-value {
   position: absolute;
-  max-width: calc(100% - #{$mat-select-arrow-size * 2});
+  max-width: calc(100% - #{($mat-select-arrow-size + $mat-select-arrow-margin) * 2});
 
   // Firefox and some versions of IE incorrectly keep absolutely
   // positioned children of flex containers in the flex flow when calculating