* dotnet/features/ioperation: (31 commits)
  Fix lambda EnC (#21291)
  Use 15.3 Preview 7 for VSI CI machines
  Add cancellation between each document.
  Remove unused private method (#21268)
  Work around SDK 1.1 issue around netcoreapp2.0
  Update Language Feature Status.md
  Const warnings shouldn't cause emit error (#20729)
  Fix the symbol test
  Choose test config based on TargetFramework
  Standardize on the portable ThrowingTraceListener
  Enforce using UnitTestPortable
  Correct the order of parameters to Version
  Clean up RunCsc/Vbc.cmd a tiny bit
  Remove usages of 'Foo' from our codebase. (#21224)
  Make RunCsc/Vbc scripts respect DOTNET_HOST_PATH
  Fix typo
  ignoring exceptions about not running on main thread
  Updating VisualStudioSymbolSearchProgressService to consume new API
  Updating visual studio references
  Accept pre-rel version number
  ...