Port CA1813 (Avoid Unsealed Attributes) to System.Runtime.Analyzers.

Unskip tests fixed by #662 and #679. 

show conditional element access sig-help after arbitrary expressions

the old model would only appear after an identifier name

don't assume that a constructor's parent is a TypeBlockSyntax

Fix variable capturing for VB lambdas in EE...

Variables may have been captured by lambdas in the original method
or in the expression, and we need to preserve the existing values of
those variables in the expression. This requires rewriting the variables
in the expression based on the closure classes from both the original
method and the expression, and generating a preamble that copies
values into the expression closure classes.

Consider the original method:
```
Shared Sub M()
    Dim x, y, z as Integer
    ...
    F(Function() x + y)
End Sub
```
and the expression in the EE: "F(Function() x + z)".
The expression is first rewritten using the closure class and the local
`<1>` from the original method: F(Function() `<1>`.x + z)
Then lambda rewriting introduces a new closure class that includes
the locals `<1>` and z, and a corresponding local
`<2>`: F(Function() `<2>`.`<1>`.x + `<2>`.z)
And a preamble is added to initialize the fields of `<2>`:
```
    <2> = New <>c__DisplayClass0()
    <2>.<1> = <1>
    <2>.z = z
```

Activating a previously failed testcase

In script and error scenarios, VB and C# syntax nodes corresponding to
constructors/methods/properties/etc. won't necessarily have a parent.
Adding some null checks to prevent a future NRE.

Fixes #317 : This HandleSolutionProjectTypeSolutionFolder was failing
because the msbuild bits in Jenkins were older bits. Now the bits should
have been updated. Hence enabling the test.

Add ErrorCode checks for properties of Dkm*AsyncResult...

It appears that DkmGetFrameArgumentsAsyncResult.Arguments may throw in some cases (rather than an empty array).  We should be resiliant to that and behave as though there are no argument values available.

I threw in a similar check for generic type arguments as well (just for good measure).

display the class's doc comment in attribute quick info

In an error parsing scenario, a VB ConstructorBlockSyntax might be
parented by something other than a TypeBlockSyntax.  Added a check for
this scenario.

EnC: Fix analysis of expression bodied indexers and query range variables

Add tests for #1709 

guard ourshelves from being called after package close at VS shutdown

handle mapped file path properly

Change the fixer to use the DocumentEditor and remove the C#\VB specific fixers.

Fixed a case for the fixer for CA1019 - if a fix is offered to make the getter of a property public, ensure that we are not making the setter public as well.

Null checks to help diagnose #1795

Reading PDB constants

Ignore accessibility in ExpressionLambdaRewriter

Ignore accessibility in ExpressionLambdaRewriter. This only affects the expression evaluator where all symbols should be accessible.

CodeModel should use SyntaxNode instead of Symbols for Parameters

Fix spelling error and remove unused method.

Do not directly cast symbol to IMethodSymbol

Fixes Internal TFS issue 1147885

CodeModel service should get the name of the parameter from the
SyntaxNode rather than the symbols since we need to get the fullname
used in the source code.

Safeguard against "Collection was modified during iteration" exception when iterating over the passed in IEnumerable of diagnostics.

Fixes #802 

Specially handle root namespace constituents in SourceNamespaceSymbol.IsDefinedInSourceTree.

Fix for issue #786

Do not directly cast symbol to IMethodSymbol

Safeguard against "Collection was modified during iteration" exception when iterating over the passed in IEnumerable of diagnostics.