- #5347
- inconsistent bounds checking caused problems after `ArrayPool<char>` fell back to `new char[2048]`
- would fail a `Debug` assertion in Debug builds and loop endlessly in Release builds
- change to `CacheTagHelper+CharBufferHtmlContent` is for correctness only
- always uses a `CharArrayBufferSource` and that returns arrays of the exact size requested
- Simplify things that used to rely on HtmlTextWriter. This behavior is
now the default.
- Simplify a whole mess of Razor TextWriter code.
- Integration test for merging of TagHelper buffers back into the 'main'
buffer.