Internal: Rethink mutations writer

[marc2332]

Depends on #729

• remove unnecessary scale factor casts
• Use of proper RealDOMAdapter cache between removals

[codecov]

Codecov Report

Attention: Patch coverage is 72.53521% with 39 lines in your changes missing coverage. Please review.

Project coverage is 73.94%. Comparing base (5d99dbe) to head (65f8d11).
Report is 1 commits behind head on main.

❗ Current head 65f8d11 differs from pull request most recent head d4dd542

Please upload reports for the commit d4dd542 to get more accurate results.

Files	Patch %	Lines
crates/renderer/src/app.rs	0.00%	25 Missing ⚠️
crates/core/src/dom/mutations_writer.rs	86.36%	6 Missing ⚠️
crates/renderer/src/window_state.rs	0.00%	5 Missing ⚠️
crates/renderer/src/renderer.rs	0.00%	2 Missing ⚠️
crates/core/src/dom/dom_adapter.rs	96.77%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #731      +/-   ##
==========================================
+ Coverage   73.91%   73.94%   +0.02%     
==========================================
  Files         198      198              
  Lines       20321    20357      +36     
==========================================
+ Hits        15020    15052      +32     
- Misses       5301     5305       +4     

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