fix(select): Alter dropdown icon to conform to spec.

Currently the dropdown icon used in the select is drastically
larger than the spec suggests:

https://material.google.com/components/text-fields.html#text-fields-single-line-text-field

Alter the SCSS slightly to reduce the size and better match
the spec.

Closes #9290

Author: topherfangio

src/components/select/select.scss

@@ -203,8 +203,8 @@ md-input-container.md-input-has-value .md-select-value {
     position: relative;
     top: 2px;
     speak: none;
-    font-size: 16px;
-    transform: scaleY(0.6) scaleX(1);
+    font-size: 13px;
+    transform: scaleY(0.5) scaleX(1);
   }
 
   &.md-select-placeholder {