Use libraryFilters flag to speed up coverage collection (#104122)

* Use libraryFilters flag to speed up coverage collection

* Allow libraryNames to be null

* Unconditionally enable the reportLines flag

* Fix analysis errors

packages/flutter_tools/bin/fuchsia_tester.dart

@@ -112,16 +112,13 @@ Future<void> run(List<String> args) async {
     Directory testDirectory;
     CoverageCollector collector;
     if (argResults['coverage'] as bool) {
+      // If we have a specified coverage directory then accept all libraries by
+      // setting libraryNames to null.
+      final Set<String> libraryNames = coverageDirectory != null ? null :
+          <String>{FlutterProject.current().manifest.appName};
       collector = CoverageCollector(
         packagesPath: globals.fs.path.normalize(globals.fs.path.absolute(argResults[_kOptionPackages] as String)),
-        libraryPredicate: (String libraryName) {
-          // If we have a specified coverage directory then accept all libraries.
-          if (coverageDirectory != null) {
-            return true;
-          }
-          final String projectName = FlutterProject.current().manifest.appName;
-          return libraryName.contains(projectName);
-        });
+        libraryNames: libraryNames);
       if (!argResults.options.contains(_kOptionTestDirectory)) {
         throwToolExit('Use of --coverage requires setting --test-directory');
       }

packages/flutter_tools/lib/src/commands/test.dart

@@ -380,7 +380,7 @@ class TestCommand extends FlutterCommand with DeviceBasedDevelopmentArtifacts {
       final String projectName = flutterProject.manifest.appName;
       collector = CoverageCollector(
         verbose: !machine,
-        libraryPredicate: (String libraryName) => libraryName.contains(projectName),
+        libraryNames: <String>{projectName},
         packagesPath: buildInfo.packagesPath
       );
     }