Implement case insensitive search in the samples index (#1518)

Closes #1517

web/samples_index/lib/src/samples.yaml

@@ -11,7 +11,7 @@ samples:
       - url: images/gallery4.png
         alt: Crane app screenshot
       - url: images/gallery5.png
-        alt: Shrine app screnshot
+        alt: Shrine app screenshot
     source: https://github.com/flutter/gallery
     web: https://gallery.flutter.dev
     description: >
@@ -416,7 +416,7 @@ samples:
       - url: images/web_dashboard1.png
         alt: Web Dashboard screenshot
       - url: images/web_dashboard2.png
-        alt: Web Dashbaord screenshot
+        alt: Web Dashboard screenshot
       - url: images/web_dashboard3.png
         alt: Web Dashboard screenshot
     source: https://github.com/flutter/samples/tree/main/experimental/web_dashboard

web/samples_index/lib/src/search.dart

@@ -6,8 +6,11 @@ bool matchesQuery(String query, String sampleAttributes) {
   if (query.isEmpty) {
     return true;
   }
-  var queryWords = query.split(' ')..removeWhere((s) => s.isEmpty);
-  var attributes = sampleAttributes.split(' ')..removeWhere((s) => s.isEmpty);
+
+  var queryWords = query.toLowerCase().split(' ')
+    ..removeWhere((s) => s.isEmpty);
+  var attributes = sampleAttributes.toLowerCase().split(' ')
+    ..removeWhere((s) => s.isEmpty);
 
   // Test for type filter
   // This will check whether a type parameter is present in the

web/samples_index/test/samples_index_test.dart

@@ -107,7 +107,9 @@ void main() {
 
       // Test if various queries match these attributes
       expect(matchesQuery('foo', attributes), false);
+      expect(matchesQuery('Foo', attributes), false);
       expect(matchesQuery('kittens', attributes), true);
+      expect(matchesQuery('Kittens', attributes), true);
       expect(matchesQuery('tag:cats', attributes), true);
       expect(matchesQuery('tag:dogs', attributes), false);
       expect(matchesQuery('package:path', attributes), true);