## Summary of the Pull Request
#7960 was caused by `UiaTextRangeBase::_blockRange` not being initialized, thus pointing to random memory. In most cases, we initialize it properly in `RuntimeClassInitialize`, however, the copying version of `RuntimeClassInitialize` doesn't actually copy it over, resulting in it still containing random memory.
NVDA (and other screen readers) occasionally use `Clone` (really just the copy initializer), resulting in this bug occurring randomly.
## PR Checklist
* [X] Closes#7960
* [X] Tests added/passed
## Validation Steps Performed
Test failed before the change, but passes after the change.
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