feat($anchorScroll): convert numeric hash targets to string

This allows `$anchorScroll(7)` to scroll to `<div id="7">` (although technically, the target ID is a
string, not a number).

Fixes #14680

Closes #15182

src/ng/anchorScroll.js

@@ -238,7 +238,8 @@ function $AnchorScrollProvider() {
     }
 
     function scroll(hash) {
-      hash = isString(hash) ? hash : $location.hash();
+      // Allow numeric hashes
+      hash = isString(hash) ? hash : isNumber(hash) ? hash.toString() : $location.hash();
       var elm;
 
       // empty hash, scroll to the top of the page

test/ng/anchorScrollSpec.js

@@ -260,6 +260,18 @@ describe('$anchorScroll', function() {
         addElements('id=top'),
         callAnchorScroll('top'),
         expectScrollingTo('id=top')));
+
+
+      it('should scroll to element with id "7" if present, with a given hash of type number', inject(
+        addElements('id=7'),
+        callAnchorScroll(7),
+        expectScrollingTo('id=7')));
+
+
+      it('should scroll to element with id "7" if present, with a given hash of type string', inject(
+        addElements('id=7'),
+        callAnchorScroll('7'),
+        expectScrollingTo('id=7')));
     });
   });