Fix typo

Fixes #37461

Annotate SymbolInfo and TypeInfo

Treat parameters and local variables as having the default state for their type before they are assigned. (#37762)

Fixes #36052

I am leaving some constructors of SymbolInfo as taking a non-null
symbol, since it appears callers do actually try to use SymbolInfo.None
in those cases. As the compiler is annotated it may be necessary to
change.

VB DIM work

Fixes #7398
Fixes #37572
Relates to https://github.com/aspnet/Razor/issues/614 and many other customer accommodations that are no longer needed.

History of this bug:  When constant folding a long sequence of string concatenations, there is an intermediate constant value for every left-hand operand.  So the total memory consumed to compute the whole concatenation was *O(n^2)*.  The compiler would simply perform this work and eventually run out of memory, simply crashing with no useful diagnostic.  Later, the concatenation implementation was instrumented so it would detect when it was likely to run out of memory soon, and would instead report a diagnostic at the last step. See https://github.com/dotnet/roslyn/commit/f177077665a5bef862014f1898b961d1759c9248.  Test `Bug529600()` was added to demonstrate that we produced a diagnostic.  However, the compiler still consumed *O(n^2)* memory for the concatenation and this test used to consume so much memory that it would cause other tests running in parallel to fail because they might not have enough memory to succeed.  So the test was disabled and eventually removed.  The compiler would still crash with programs containing large string concatenations, or consume huge amounts of memory and take a long time before reporting a diagnostic, so the underlying problem had not been addressed.

Here we have revised the implementation of constant folding string concatenations so that it requires *O(n)* memory and remove the old instrumentation.  As a consequence the test `Bug529600()` now runs very quickly and does not consume gobs of memory.

Refactorings ordering report applicableToSpan

Merge branch 'refactoringsOrdering-reportSpan' of https://github.com/petrroll/roslyn into refactoringsOrdering-reportSpan

Generate IOperation visitors and simple implementation classes

Merge master to release/dev16.4-preview1

Fix operations generator target platform.

Closes #35824.

Closes #35820.

VB: Do not require to implement a method representing a re-abstraction of an interface method from base interface.

Closes #35823.

Allow implementation of virtual interface methods in VB.

Implement Quick Info support for 'inheritdoc'

Add a tool which generates a reasonable C# grammar facsimile from our syntactic model.

Don't synthesize a parameter list out of nowhere.

Enum member formatting should follow csharp_space_around_declaration_statements

Update partial load dialog string to better match task center.

Move to new ilasm version

Merge master to release/dev16.4-preview1