[kernel] Cache patch-classes.

[kernel] Cache patch-classes.

Via kernel we create PatchClasses to make sure the correct script is set
for functions and fields. Currently we create a new PatchClass each time
we need one, but often an old one could easily be reused.
This CL implements a simple caching-scheme and often uses a cached version.
Because some are requested out-of-order "duplicate" PatchClasses can still
be created though.

BUG=
R=kmillikin@google.com

Committed: https://github.com/dart-lang/sdk/commit/7952514f083880402afcf84be9c240e5407b9bf5

[jensj, 2017-06-30 07:59:24]

jensj@google.com changed reviewers:
+ kmillikin@google.com

[Kevin Millikin (Google), 2017-08-08 09:38:48]

lgtm

[jensj, 2017-08-09 09:01:33]

Description was changed from

==========
[kernel] Cache patch-classes.

Via kernel we create PatchClasses to make sure the correct script is set
for functions and fields. Currently we create a new PatchClass each time
we need one, but often an old one could easily be reused.
This CL implements a simple caching-scheme and often uses a cached version.
Because some are requested out-of-order "duplicate" PatchClasses can still
be created though.

BUG=
==========

to

==========
[kernel] Cache patch-classes.

Via kernel we create PatchClasses to make sure the correct script is set
for functions and fields. Currently we create a new PatchClass each time
we need one, but often an old one could easily be reused.
This CL implements a simple caching-scheme and often uses a cached version.
Because some are requested out-of-order "duplicate" PatchClasses can still
be created though.

BUG=
R=kmillikin@google.com

Committed:
https://github.com/dart-lang/sdk/commit/7952514f083880402afcf84be9c240e5407b9bf5
==========

[jensj, 2017-08-09 09:01:35]

Committed patchset #1 (id:1) manually as
7952514f083880402afcf84be9c240e5407b9bf5 (presubmit successful).