perf(ivy): improve styling performance (#33326)

change the existing implementation from using

```
string.split(/\s+/);
```

to a char scan which performers the same thing.

The reason why `split(/\s+/)` is slow is that:
- `/\s+/` allocates new `RegExp` every time this code executes.
- `RegExp` scans are a lot more expensive because they are more powerful.

PR Close #33326

packages/core/test/render3/util/styling_utils_spec.ts

@@ -0,0 +1,26 @@
+/**
+ * @license
+ * Copyright Google Inc. All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.io/license
+ */
+
+import {splitOnWhitespace} from '@angular/core/src/render3/util/styling_utils';
+
+describe('styling_utils', () => {
+  describe('splitOnWhitespace', () => {
+    it('should treat empty strings as null', () => {
+      expect(splitOnWhitespace('')).toEqual(null);
+      expect(splitOnWhitespace('  ')).toEqual(null);
+      expect(splitOnWhitespace(' \n\r\t ')).toEqual(null);
+    });
+
+    it('should split strings into parts', () => {
+      expect(splitOnWhitespace('a\nb\rc')).toEqual(['a', 'b', 'c']);
+      expect(splitOnWhitespace('\ta-long\nb-long\rc-long ')).toEqual([
+        'a-long', 'b-long', 'c-long'
+      ]);
+    });
+  });
+});