Do not needlessly access isDirty

[igorT]

We were entangling isDirty by doing a get(this, 'isDirty'); even when no one had read our dirty state. In some edge cases, this could result in rerendering errors, and was also not great for performance.

[github-actions]

Performance Report for 00f4796

Scenario - materializing: ⚠️ Performance regressed

⚠️ duration
phase estimated regression +41ms [14ms to 75ms] OR +0.85% [0.29% to 1.53%]
☑️ Phase [navigationStart] => [start-loading]
phase no difference [-3ms to 5ms]
☑️ Phase [start-loading] => [pushed-payload]
phase no difference [-10ms to 27ms]
⚠️ Phase [pushed-payload] => [end-loading]
phase estimated regression +35ms [21ms to 50ms] OR +1.83% [1.11% to 2.64%]
☑️ Phase [end-loading] => [Test End]
phase no difference [0ms to 1ms]

Scenario - rendering: ☑️ Performance is stable

☑️ duration
phase no difference [-8ms to 4ms]
☑️ Phase [navigationStart] => [start-loading]
phase no difference [-2ms to 5ms]
☑️ Phase [start-loading] => [pushed-payload]
phase no difference [-1ms to 0ms]
☑️ Phase [pushed-payload] => [end-loading]
phase no difference [0ms to 0ms]
☑️ Phase [end-loading] => [Test End]
phase no difference [-5ms to 2ms]

addressed feedback