Reapply "Use a single file for app snapshots."

Reapply "Use a single file for app snapshots."

 - Don't read script to check for an app snapshot if it is a pipe. Fixes loading source from a pipe.
 - Fix windows and fushsia builds.

R=asiva@google.com

Committed: https://github.com/dart-lang/sdk/commit/3d00ecdc8f8e4da4a0b3f48103a7e0d7845136a7

[rmacnak, 2016-10-13 23:51:17]

rmacnak@google.com changed reviewers:
+ asiva@google.com

[siva, 2016-10-14 00:10:24]

lgtm

[rmacnak, 2016-10-14 16:57:58]

Description was changed from

==========
Reapply "Use a single file for app snapshots."

 - Don't read script to check for an app snapshot if it is a pipe. Fixes loading
source from a pipe.
 - Fix windows and fushsia builds.
==========

to

==========
Reapply "Use a single file for app snapshots."

 - Don't read script to check for an app snapshot if it is a pipe. Fixes loading
source from a pipe.
 - Fix windows and fushsia builds.

R=asiva@google.com

Committed:
https://github.com/dart-lang/sdk/commit/3d00ecdc8f8e4da4a0b3f48103a7e0d7845136a7
==========

[rmacnak, 2016-10-14 16:58:00]

Committed patchset #2 (id:20001) manually as
3d00ecdc8f8e4da4a0b3f48103a7e0d7845136a7 (presubmit successful).

[zra, 2016-10-18 16:16:44]

zra@google.com changed reviewers:
+ zra@google.com

[zra, 2016-10-18 16:16:46]

https://codereview.chromium.org/2416973003/diff/20001/runtime/bin/main.cc
File runtime/bin/main.cc (right):

https://codereview.chromium.org/2416973003/diff/20001/runtime/bin/main.cc#new...
runtime/bin/main.cc:1313: if (File::GetType(script_name, true) != File::kIsFile)
{
On Windows, this calls Dart_ScopeAllocate, which fails as various thread locals
haven't been initialized, yet, causing all tests to fail.