Added support for Gradle productFlavors that are not only lowercase (#22767)

Fixes https://github.com/flutter/flutter/issues/19507

packages/flutter_tools/lib/src/android/gradle.dart

@@ -503,8 +503,8 @@ class GradleProject {
   String _productFlavorFor(BuildInfo buildInfo) {
     if (buildInfo.flavor == null)
       return productFlavors.isEmpty ? '' : null;
-    else if (productFlavors.contains(buildInfo.flavor.toLowerCase()))
-      return buildInfo.flavor.toLowerCase();
+    else if (productFlavors.contains(buildInfo.flavor))
+      return buildInfo.flavor;
     else
       return null;
   }

packages/flutter_tools/test/android/gradle_test.dart

@@ -138,6 +138,10 @@ someOtherTask
       expect(project.assembleTaskFor(const BuildInfo(BuildMode.release, 'paid')), 'assemblePaidRelease');
       expect(project.assembleTaskFor(const BuildInfo(BuildMode.release, 'unknown')), isNull);
     });
+    test('should respect format of the flavored build types', () {
+      final GradleProject project = GradleProject(<String>['debug'], <String>['randomFlavor'], fs.directory('/some/dir'));
+      expect(project.assembleTaskFor(const BuildInfo(BuildMode.debug, 'randomFlavor')), 'assembleRandomFlavorDebug');
+    });
   });
 
   group('Gradle local.properties', () {