rework LocalLibraryContributor to resolve referenced units

pkg/analysis_server/lib/src/services/completion/dart/completion_manager.dart

Index: pkg/analysis_server/lib/src/services/completion/dart/completion_manager.dart
diff --git a/pkg/analysis_server/lib/src/services/completion/dart/completion_manager.dart b/pkg/analysis_server/lib/src/services/completion/dart/completion_manager.dart
index 5cfdacef0120bf9de9db13431207ad612a3c9b19..f9665c5ba07c1af3fc40f728f18e509f0464fff0 100644
--- a/pkg/analysis_server/lib/src/services/completion/dart/completion_manager.dart
+++ b/pkg/analysis_server/lib/src/services/completion/dart/completion_manager.dart
@@ -267,6 +267,27 @@ class DartCompletionRequestImpl implements DartCompletionRequest {
     _updateTargets(resolvedUnit);
   }
 
+  @override
+  Future<List<CompilationUnitElement>> resolveUnits() async {
+    checkAborted();
+    LibraryElement libElem = libraryElement;
+    if (libElem == null) {
+      return null;
+    }
+    List<CompilationUnitElement> resolvedUnits = <CompilationUnitElement>[];
+    for (CompilationUnitElement unresolvedUnit in libElem.units) {
+      CompilationUnit unit = await _computeAsync(
+          this,
+          new LibrarySpecificUnit(libElem.source, unresolvedUnit.source),
+          RESOLVED_UNIT3,
+          performance,
+          'resolve library unit');

[Brian Wilkerson, 2016/02/12 20:42:07]

Do we want to checkAborted() after returning from an async call?

[danrubel, 2016/02/12 20:54:23]

Good catch! Done.

+      CompilationUnitElement resolvedUnit = unit?.element;
+      resolvedUnits.add(resolvedUnit);

[Brian Wilkerson, 2016/02/12 20:42:07]

Do we want to check for null before adding the unit to the list? I know we test
for it later, but it might be better to test for it here.

[danrubel, 2016/02/12 20:54:23]

Good idea. Done.

+    }
+    return resolvedUnits;
+  }
+
   /**
    * Update the completion [target] and [dotTarget] based on the given [unit].
    */