Reapply "Switch to the new analysis driver in analyzer_cli."

pkg/analyzer_cli/lib/src/analyzer_impl.dart

Index: pkg/analyzer_cli/lib/src/analyzer_impl.dart
diff --git a/pkg/analyzer_cli/lib/src/analyzer_impl.dart b/pkg/analyzer_cli/lib/src/analyzer_impl.dart
index 5df078a224d8cf0899f0adb8f88cb04a38eea996..73ff30b2d4a2124085ca2224ae23ddf5a55d0f8d 100644
--- a/pkg/analyzer_cli/lib/src/analyzer_impl.dart
+++ b/pkg/analyzer_cli/lib/src/analyzer_impl.dart
@@ -266,8 +266,9 @@ class AnalyzerImpl {
       if (analysisDriver != null) {
         String path = librarySource.fullName;
         analysisDriver.priorityFiles = [path];
-        AnalysisResult analysisResult = await analysisDriver.getResult(path);
-        return analysisResult.unit.element.library;
+        UnitElementResult elementResult =
+            await analysisDriver.getUnitElement(path);
+        return elementResult.element.library;
       } else {
         return context.computeLibraryElement(librarySource);
       }