Add and use AnalysisCache.sources getter.

Add and use AnalysisCache.sources getter.

This is not ideal, we might still want to start managing 'containingLibraries' at some point.

But it speeds up switching between file 10x - DartCompletionCache request of all top-level elements takes now about 170 ms, vs. 1800 ms before.

Also, we need "sources" in many places of AnalysisContext.

R=brianwilkerson@google.com
BUG=

Committed: https://github.com/dart-lang/sdk/commit/deddddc9e51cc6d04b0a6691f34f7d480d2cb8c9

[Brian Wilkerson, 2015-05-21 13:52:31]

LGTM

https://codereview.chromium.org/1149893004/diff/1/pkg/analyzer/lib/src/contex...
File pkg/analyzer/lib/src/context/cache.dart (right):

https://codereview.chromium.org/1149893004/diff/1/pkg/analyzer/lib/src/contex...
pkg/analyzer/lib/src/context/cache.dart:821: void _addSource(AnalysisTarget
target) {
I was confused when I first saw this method being used because I expected it to
expect the argument to be a Source. Perhaps rename it to "_addIfSource"? (I'm
not sure that's much better, though.) Or maybe just in-line it, given that it's
only used in one place.

https://codereview.chromium.org/1149893004/diff/1/pkg/analyzer/test/src/conte...
File pkg/analyzer/test/src/context/cache_test.dart (right):

https://codereview.chromium.org/1149893004/diff/1/pkg/analyzer/test/src/conte...
pkg/analyzer/test/src/context/cache_test.dart:869: class _TestAnalysisTarget
implements AnalysisTarget {
Don't we already have this class somewhere?

[scheglov, 2015-05-21 15:33:31]

Committed patchset #1 (id:1) manually as
deddddc9e51cc6d04b0a6691f34f7d480d2cb8c9 (presubmit successful).