Fix icon button icon size
Fix icon button icon size

This fixes the css changes introduced in https://crrev.com/c/3967796,
which caused the icons in round and small/tiny buttons to be of the
wrong size when trying to explicitly set an icon size.

Bug: 1297533
Change-Id: I8c9649b301db5abe063e44e329f8b1fec189095d
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/3966178
Commit-Queue: Danil Somsikov <f16a5ee11618cab93684e694f9aa762d34f02920@chromium.org>
Commit-Queue: Wolfgang Beyer <573aa99bb19da47d816981118f95c945310dd3f4@chromium.org>
Auto-Submit: Wolfgang Beyer <573aa99bb19da47d816981118f95c945310dd3f4@chromium.org>
Reviewed-by: Danil Somsikov <f16a5ee11618cab93684e694f9aa762d34f02920@chromium.org>

ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend