fix(icon): when specified, the defaultFontSet class should be used.

src/components/icon/iconDirective.js

@@ -241,23 +241,22 @@ function mdIconDirective($mdIcon, $mdTheming, $mdAria ) {
       if (!scope.svgIcon && !scope.svgSrc) {
 
         if (scope.fontIcon) {
-          element.addClass('md-font');
-          element.addClass(scope.fontIcon);
+          element.addClass('md-font ' + scope.fontIcon);
         }
 
         if (scope.fontSet) {
           element.addClass($mdIcon.fontSet(scope.fontSet));
         }
 
-        // For Material Design font icons, the class '.material-icons'
-        // is auto-added IF a style has not been specified
-
-        if (!scope.fontIcon && !scope.fontSet && !angular.isDefined(attr.class)) {
-
-            element.addClass('material-icons');
+        if (shouldUseDefaultFontSet()) {
+          element.addClass($mdIcon.fontSet());
         }
+
       }
 
+      function shouldUseDefaultFontSet() {
+        return !scope.fontIcon && !scope.fontSet && !attr.hasOwnProperty('class');
+      }
     }
   }
 }

src/components/icon/iconDirective.spec.js

@@ -140,6 +140,18 @@ describe('mdIcon directive', function() {
 
       });
 
+      it('should support custom default fontset', function() {
+        $mdIconProvider.defaultFontSet('fa');
+
+        el = make( '<md-icon></md-icon>');
+        expect( clean(el.attr('class')) ).toEqual("fa");
+
+        el = make( '<md-icon>apple</md-icon>');
+        expect(el.text()).toEqual('apple');
+        expect( clean(el.attr('class')) ).toEqual("fa");
+
+      });
+
       it('should support clearing an invalid font alias', function() {
 
         el = make( '<md-icon md-font-set="none" class="custom-cake"></md-icon>');