Update corefx refs to -rc2-24027

Update to DSR 1.0.8-rc2-60426-09

Revert the commit that removed IOperation Feature flag 

Promote APIs shipped in VS 2015 Update 2

Merge PublicAPI.Shipped.txt and PublicAPI.Unshipped.txt file changes
made against Update 2 with current state of stabilization branch.

Move lines appearing in PublicAPI.Unshipped.txt files to
PublicAPI.Shipped.txt files and re-sort the latter.

Note: VB scripting APIs and APIs for IOperation continue to remain
unshipped.

This reverts commit 92ff3f8d.

Add netstandard TFM to workspaces nuspecs

Merge master to stabilization

Merge master into stabilization

Include System.IO.FileSystem in Roslyn.Build.Util package

fixed build dedup bug caused by recent change.

Merge stabilization into master

Checking in the IDE test plan document

OOP #1 - new analyzer engine that uses CompilerAnalyzer model

added flag for including project non local result.

make analyzer driver won't get into action execution when there is actually no action for the analyzer

Do not throw if initialized by Winforms UI thread
Fixes https://github.com/dotnet/roslyn/issues/10510

Fix CPC

Don't block in library code.

Earlier the perf test runner using CPC was broken. This change fixes that.

With this change, we will be running CPC a little different than what we used to.
Earlier, we run CPC for 'n' of iterations and the first iteration should to be a
warmup iteration. Each iteration runs all the tests once.

Now, we run CPC for 'n' iterations for each test and 'n' is defined by each test.
The first iteration is, again, a warmup iteration and the rest are considered for the
metrics calculation. With this model, each iteration will run just one test instead of
running all the tests in an iteration. This helps in making the warmup iteration, a
true warmup iteration.

Minor changes:
Since the test csx returns an object now, the test related information has been
moved to the corresponding test csx files.

Simplest fix for this issue to be considered for Micro-Update

added assert for GetEffectiveDiagnostics

removed unnecessary GetEffectiveDiagnostics call for diagnostics from CompilationWithAnalyzers and other code clean up.

added some comments, code clean up and rename.