Revert package logging (moving to status pages).

Context:

#24900

BUG=24900
R=brianwilkerson@google.com, scheglov@google.com

Review URL: https://codereview.chromium.org/1441673003 .

pkg/analysis_server/lib/src/context_manager.dart

@@ -838,16 +838,7 @@ class ContextManagerImpl implements ContextManager {
             return new CustomPackageResolverDisposition(resolver);
           }
         }
-
-        // Notify server that no `.packages` file was found (and there is no
-        // alternative resolver provider).
-        //
-        // NOTE that this is a temporary measure and will be replaced with
-        // a proper call to diagnostics when support is there.
-        // https://github.com/dart-lang/sdk/issues/24900
-        AnalysisEngine.instance.logger.logError(
-            'No `.packages` for $folder, falling back to `pub`.');
-
+
         ServerPerformanceStatistics.pub.makeCurrentWhile(() {
           packageMapInfo = _packageMapProvider.computePackageMap(folder);
         });