Fix for reporting not analyzed parts with the new analysis driver.

pkg/analyzer_cli/lib/src/driver.dart

Index: pkg/analyzer_cli/lib/src/driver.dart
diff --git a/pkg/analyzer_cli/lib/src/driver.dart b/pkg/analyzer_cli/lib/src/driver.dart
index e91d07ef262d6373d7af382528fca49a2114cbd7..067491fde610dc26c6e1269fe12c13bf61cd5b1d 100644
--- a/pkg/analyzer_cli/lib/src/driver.dart
+++ b/pkg/analyzer_cli/lib/src/driver.dart
@@ -244,10 +244,17 @@ class Driver implements CommandLineStarter {
     // Check that each part has a corresponding source in the input list.
     for (Source part in parts) {
       bool found = false;
-      for (var lib in context.getLibrariesContaining(part)) {
-        if (libUris.contains(lib.uri)) {
+      if (analysisDriver != null) {
+        var partFile = analysisDriver.fsState.getFileForPath(part.fullName);
+        if (libUris.contains(partFile.library?.uri)) {
           found = true;
         }
+      } else {
+        for (var lib in context.getLibrariesContaining(part)) {
+          if (libUris.contains(lib.uri)) {
+            found = true;
+          }
+        }
       }
       if (!found) {
         errorSink.writeln("${part.fullName} is a part and cannot be analyzed.");