Drop SummaryBuilder constructor's optional "strong" parameter.

Note that although this change is inside analyzer/lib/src, in practice
it is a breaking change to the analyzer API, since several clients
invoke the SummaryBuilder constructor.  Fortunately we can make
breaking changes now since we have not yet published version 0.33.* of
the analyzer.

To my knowledge, all clients that we care about keeping synchronized
to the bleeding edge version of the analyzer have been modified so
that they no longer pass in the optional parameter.  The remaining
clients shouldn't be affected since their pubspecs still point to
analyzer version 0.32.*.

Change-Id: I627bb7b1242e8e36ec82927ed8fe722b5b249fd6
Reviewed-on: https://dart-review.googlesource.com/73000
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
Commit-Queue: Paul Berry <paulberry@google.com>
diff --git a/pkg/analyzer/lib/src/summary/summary_file_builder.dart b/pkg/analyzer/lib/src/summary/summary_file_builder.dart
index b53d5ac..3ef4a6d 100644
--- a/pkg/analyzer/lib/src/summary/summary_file_builder.dart
+++ b/pkg/analyzer/lib/src/summary/summary_file_builder.dart
@@ -33,7 +33,7 @@
    * TODO(paulberry): remove optional "strong" parameter once all callers have
    * stopped passing it in.
    */
-  SummaryBuilder(this.librarySources, this.context, [bool strong]);
+  SummaryBuilder(this.librarySources, this.context);
 
   /**
    * Create an SDK summary builder for the dart SDK at the given [sdkPath].