* [web] Remove left/top/transform reset since all code paths now set ltwh
* Remove unused style var
* Handle path=null , address review comments
* Added comment for reset code

* Fix cachedLastStyle state leak across canvases. Reduce ctx.font reset calls.

* Remove font set test

This change is part of an LSC in Fuchsia, and is a functionality no-op.

Fixes fxbug.dev/50759
Co-authored-by: NGabriel Schine <thatguy@google.com>

This reverts commit b5aedb30 and relands #17712.

Fixes flutter/flutter#53288 and flutter/flutter#41654.

Together with #17791, this reland addresses some of Jim's concerns in the original PR #17712.

The major part of this PR is still the same as the original PR, and the performance / golden image impacts should be the same.

This reverts commit a5e0b2f2.

The way transactions were added changed in
https://github.com/flutter/engine/commit/68fd8334889610af08cbfc2828f91cf14faf3f1d.
This broke rendering using both Metal and OpenGL when no implicit transaction
was present on the transaction stack. The failure models differ based on Metal
vs. OpenGL and iOS/device versions. On older versions of iOS, rendering would
consume memory till exhaustion. On newer iOS versions, rendering would be stuck
(till a timeout). This patch brings transaction management back in line with as
it was earlier and also makes the Metal backend resilient to transactions being
present on the transaction stack at all. Since this is still quite brittle,
transaction management must be moved to IOSSurface as a followup.

Fixes https://github.com/flutter/flutter/issues/55784.