I've done some manual testing, but there are no unit tests.

Existing unit tests are pass, except for ParseXml.Bug674567.  The fix is
either to change the baseline or to merge
https://github.com/dotnet/roslyn/pull/3957.

Conflicts:
	src/Compilers/VisualBasic/Portable/Scanner/Scanner.vb
	src/Compilers/VisualBasic/Portable/Syntax/CompilationUnitSyntax.vb
	src/Compilers/VisualBasic/Test/Semantic/Compilation/CompilationAPITests.vb