Re-enable passing test TestFixAllInDocument_QualifyWithThis. Matt Warren fixed the underlying issue in SyntaxTree.GetChanges(SyntaxTree).

In a handful of places, Task.FromResult(true), Task.FromResult(false), and Task.FromResult(default(T)) were being used, even though equivalent cached tasks are available in SpecializedTasks. This commit just changes those ~20 call sites to use already cached tasks.

Also added a smart, where, if we are in an expression bodied member context
and if the right side of arrow clause contains a block, we generate local
as if we're in a block context. This leads to an experience where we can
keep the expression body syntax and also have introduce a local (since we
have a block) without having to rewrite it to an equivalent full bodied
member whose body is always a block.

Fixes #540 "Stale rename entries in the lightbulb menu"

Prior to this change, dismissed rename tracking sessions continued to
provide codefixes which would silently fail when invoked, without
completing the rename operation.

With this change, we now do the following when rename tracking is
manually dismissed:

- Trigger the diagnostic service to reanalyze the document, thus
removing the rename tracking diagnostic.
- Stop providing a codefix when requested
- Show a dialog if a cached codefix is invoked explaining that the
rename was not performed.

Here are the there user scenarios:

1. The user dismisses rename tracking

    - The lightbulb will continue to show in the margin, regardless of
whether any codefix/refactoring is actually still available.

2. The user expands the lightbulb without it ever having been expanded
before.

    - In this case, we are queried for fixes and will not return any, so
either the lightbulb will disappear or it will contain other relevant
codefixes/refactorings at that position, excluding rename.

3. The user expands the lightbulb after it was previously expanded.

    - Our fix was already cached, so we can only give a reasonable message
when it is invoked.

Once #885 is fixed, we can instead implement IDiagnosticUpdateSource and
avoid forcing diagnostic reanalysis.

Bodied Members. This commit adds preliminary support to generate fields
and a few tests for C#. This is a more straightforward scenario, than
offering to generate locals, in which case we have to rewrite the
expression bodied member to an equivalent normal one. Support for such
scenarios and lots more test to follow in future commits.

Fixes #725: 'this' keyword should be available in the completion list, in the
context of member expression body.

Been almost a month since the code formatter was run so this change was
a bit larger than would be expected for a normal (weekly) update.  Diffs
mostly around:

- Whitespace changes
- Missing copyright headers
- Missing visibility modifiers

all tests passing. now StateManager owns all state related operation.

Fix #872 : Indent appropriately on Enter inside
InterpolatedVerbatimString

If the Return is issued in the context of the InterpolatedString, the
next line is placed at the column 0

If the Return is issued inside the Interpolated syntax of the
InterpolatedVerbatimString then place the next line accordingly to the
indentation rule

Completion on backspace uses the caret position to determine if it should trigger, which involves inspecting the subject buffer. It did not map the text view caret position onto the subject buffer position. This resulted in crashes in projection scenarios when the surface buffer was longer than the subject buffer.

Automatic brace completion of "(" parses as a cast, but the user might
be trying to type a parenthesized expression.

1. Add declaration info for ArrowExpressionClauseSyntax: For properties and indexers, this node declares the getter method symbol whose IsImplicitlyDeclared flag is false and hence the analyzer symbol actions need to be invokedfor this getter.

2. Previously executable code block actions for nodes within ArrowExpressionClauseSyntax were executed with parenting property symbol as the owning symbol. This change fixes it to have the declared getter method symbol as the owner of executable block for ArrowExpressionClauseSyntax.

1) Don't crash command line builds when reporting analyzer diagnostics. Reporting analyzer diagnostics may involve invoking user code for LocalizableString message, which may throw while finding resources or for other unknown reasons. We catch exceptions from these callbacks and report a diagnostic with the inner exception message.
I verified that this addressed the crash seen in #271 and #813 and we started seeing this new info diagnostic.

2) Workaround for #271: The underlying cause of the crash is that our assembly resolver/CLR is unable to fallback to the main assembly for resources and ends up looking for the satellite resource assembly. We had seen this crash quite a while back, but it went away and this seems to have come up again. Workaround, as applied back then, is to mark the analyzer assembly with NeutralResourcesLanguageAttribute.
I verified that adding this attribute to our core analyzer assemblies caused the resource to be correctly found and we don't even see the exception diagnostic from (1) above, but instead the actual diagnostic reported by the analyzer.

Fix #409:
Add explicit StringComparison.Ordinal or StringComparison.OrdinalIgnoreCase where it was intended,
or replace single-char string literals with chars literals.
Also, provide InvariantCulture in TryParse where it was intended.

Fixes #791: The code '\*' is parsed as MultiLine Comment even with the
presence of the corresponding '*\' in some cases. Hence, OutLining Span
creator should not assume that '*\' will always be present for Multiline
Comment and handle the creation appropriately

Fix for #565: Syntax node actions are not called for field declarations in compiler analyzer driver if the declaration defines multiple variables

Simplify logic for execution of syntax node actions for field declarations: If there are multiple decls, execute syntax node actions for entire field decl (and its descendants) when processing symbol declared event for first field within it, and skip syntax node actions for rest of fields defined within that declaration.
Current logic is unnecessarily complex in that it tries to execute syntax node actions for individual variable declarators when processing corresponding field symbol declared event, and executes the node actions for shared nodes (e.g. defining type syntax node) when processing first field symbol.

move duplicate localized string to WorkspacesResources and remove all occurences of the hard-coded version

Fixes #466 "Use a 'TriggerDiagnosticDescriptor' for the rename tracking
diagnostic"

Updates the RenameTrackingDiagnosticAnalyzer to use a
TriggerDiagnosticDescriptor, which prevents the diagnostic title from
appearing in the preview area of the lightbulb. We now pass the
RenameFrom and RenameTo names as part of the Diagnostic's property bag
and construct the localized codefix title based on these in the codefix
itself.

VB does not support virtual events.

In string interpolations, parentheses can't be removed if they surround
some expression that includes a : or :: token. Othewise, a parsing
ambuity will be introduced due to the : that delimits the format clause
(i.e. $"{number:x4}").

Fixes Issue #724.