Cherry-pick r44373, r44378, and r44275.

pkg/analyzer/lib/src/generated/engine.dart

Index: pkg/analyzer/lib/src/generated/engine.dart
diff --git a/pkg/analyzer/lib/src/generated/engine.dart b/pkg/analyzer/lib/src/generated/engine.dart
index 399959cd4ed2bba0360878d89f0da50d81eb90dc..bf4be15eec24c7dcc028027ba905563ace3900e0 100644
--- a/pkg/analyzer/lib/src/generated/engine.dart
+++ b/pkg/analyzer/lib/src/generated/engine.dart
@@ -451,6 +451,13 @@ abstract class AnalysisContext {
   void set sourceFactory(SourceFactory factory);
 
   /**
+   * Return an array containing all of the sources known to this context.
+   *
+   * @return all of the sources known to this context
+   */
+  List<Source> get sources;
+
+  /**
    * Returns a type provider for this context or throws [AnalysisException] if
    * `dart:core` or `dart:async` cannot be resolved.
    */
@@ -1447,6 +1454,16 @@ class AnalysisContextImpl implements InternalAnalysisContext {
     _invalidateAllLocalResolutionInformation(true);
   }
 
+  @override
+  List<Source> get sources {
+    List<Source> sources = new List<Source>();
+    MapIterator<Source, SourceEntry> iterator = _cache.iterator();
+    while (iterator.moveNext()) {
+      sources.add(iterator.key);
+    }
+    return sources;
+  }
+
   /**
    * Return a list of the sources that would be processed by [performAnalysisTask]. This
    * method duplicates, and must therefore be kept in sync with, [getNextAnalysisTask].