Turn off summaries in context when building summary from AST.

Turn off summaries in context when building summary from AST.

When building summaries from ASTs, we only use the context to read
source files; we don't need it to provide an element model.  Therefore,
we can save some time by turning off the context's use of summaries,
because this prevents it from trying to eagerly deserialize the
summaries of dart:async and dart:core.

Saves a significant amount of time when building a summary of a small
package using ASTs.  For example, saves ~37% of time when building a
strong mode summary of the "yaml" package.

R=brianwilkerson@google.com

Committed: https://github.com/dart-lang/sdk/commit/2a5db6841bf99b96e3a1c14165190b1c8fa67622

[Paul Berry, 2016-04-12 21:15:51]

paulberry@google.com changed reviewers:
+ brianwilkerson@google.com

[Brian Wilkerson, 2016-04-12 21:27:05]

lgtm

[Paul Berry, 2016-04-14 12:59:06]

Description was changed from

==========
Turn off summaries in context when building summary from AST.

When building summaries from ASTs, we only use the context to read
source files; we don't need it to provide an element model.  Therefore,
we can save some time by turning off the context's use of summaries,
because this prevents it from trying to eagerly deserialize the
summaries of dart:async and dart:core.

Saves a significant amount of time when building a summary of a small
package using ASTs.  For example, saves ~37% of time when building a
strong mode summary of the "yaml" package.
==========

to

==========
Turn off summaries in context when building summary from AST.

When building summaries from ASTs, we only use the context to read
source files; we don't need it to provide an element model.  Therefore,
we can save some time by turning off the context's use of summaries,
because this prevents it from trying to eagerly deserialize the
summaries of dart:async and dart:core.

Saves a significant amount of time when building a summary of a small
package using ASTs.  For example, saves ~37% of time when building a
strong mode summary of the "yaml" package.

R=brianwilkerson@google.com

Committed:
https://github.com/dart-lang/sdk/commit/2a5db6841bf99b96e3a1c14165190b1c8fa67622
==========

[Paul Berry, 2016-04-14 12:59:07]

Committed patchset #1 (id:1) manually as
2a5db6841bf99b96e3a1c14165190b1c8fa67622 (presubmit successful).