With the parser code in the same library as the DOM classes, the
`pkg/analyzer/tool/messages/generate.dart` program, which generates all
of the diagnostic classes and diagnostics, _depends_ on a library
with a `parse` method which depends on these diagnostic classes (in
order to report errors while parsing HTML). This means that if
there is any existing error (like an unknown identifier) in the
existing error codes, it is impossible to generate the error codes.
Since we don't need the `parse` method to generate diagnostics, we
split up the library and remove the indirect dependency.
Separating the parser code out removes the loop.
Change-Id: Ifb9e9fd979e341ae64a1ed49aaf3758d3dcf1dee
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/287220
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
Commit-Queue: Samuel Rawlins <srawlins@google.com>
Parker Lougheed