Fix icon size regression in Switcher (#13767)

* Fix icon size regression in Switcher

In #12901, a small margin was introduced to the IconButton component when text was present. This caused an issue with block icons, scaling them down when they shouldn't be. A 20x20px icon should show as 20x20, and a 24x24px icon should show as 24x24px.

The additional margin was applied even when the IconButton didn't actually have text. It simply needed `children`, and in the case of the Switcher, it has a dropdown arrow. Combined with the fixed width of the switcher, that meant a 24x24 icon would be rendered as 20x24.

This PR adds a length check so if your IconButton includes more than 2 letters, it's considered to have a text label. This fixes the issue. But as you can tell, maybe it's not the best way to check whether there's text or not. Suggestions most welcome.

* Address feedback.

Props @aduth for essentially writing this PR.

packages/editor/src/components/block-switcher/index.js

@@ -116,10 +116,13 @@ export class BlockSwitcher extends Component {
 								label={ label }
 								tooltip={ label }
 								onKeyDown={ openOnArrowDown }
-							>
-								<BlockIcon icon={ icon } showColors />
-								<SVG className="editor-block-switcher__transform" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><Path d="M6.5 8.9c.6-.6 1.4-.9 2.2-.9h6.9l-1.3 1.3 1.4 1.4L19.4 7l-3.7-3.7-1.4 1.4L15.6 6H8.7c-1.4 0-2.6.5-3.6 1.5l-2.8 2.8 1.4 1.4 2.8-2.8zm13.8 2.4l-2.8 2.8c-.6.6-1.3.9-2.1.9h-7l1.3-1.3-1.4-1.4L4.6 16l3.7 3.7 1.4-1.4L8.4 17h6.9c1.3 0 2.6-.5 3.5-1.5l2.8-2.8-1.3-1.4z" /></SVG>
-							</IconButton>
+								icon={ (
+									<Fragment>
+										<BlockIcon icon={ icon } showColors />
+										<SVG className="editor-block-switcher__transform" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><Path d="M6.5 8.9c.6-.6 1.4-.9 2.2-.9h6.9l-1.3 1.3 1.4 1.4L19.4 7l-3.7-3.7-1.4 1.4L15.6 6H8.7c-1.4 0-2.6.5-3.6 1.5l-2.8 2.8 1.4 1.4 2.8-2.8zm13.8 2.4l-2.8 2.8c-.6.6-1.3.9-2.1.9h-7l1.3-1.3-1.4-1.4L4.6 16l3.7 3.7 1.4-1.4L8.4 17h6.9c1.3 0 2.6-.5 3.5-1.5l2.8-2.8-1.3-1.4z" /></SVG>
+									</Fragment>
+								) }
+							/>
 						</Toolbar>
 					);
 				} }