[dart:html] add syntax highlighting to code blocks

Change-Id: I7dc008c01e776be8010da4845b3dc95643e34194
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/202401
Auto-Submit: Sigmund Cherem <sigmund@google.com>
Commit-Queue: Sigmund Cherem <sigmund@google.com>
Commit-Queue: Srujan Gaddam <srujzs@google.com>
Reviewed-by: Srujan Gaddam <srujzs@google.com>
diff --git a/sdk/lib/html/doc/WORKAROUNDS.md b/sdk/lib/html/doc/WORKAROUNDS.md
index d3d8456..39a1c06 100644
--- a/sdk/lib/html/doc/WORKAROUNDS.md
+++ b/sdk/lib/html/doc/WORKAROUNDS.md
@@ -26,7 +26,7 @@
 missing the API `readAsBinaryString` ([#42834][]). We can work around this by
 doing something like the following:
 
-```
+```dart
 import 'dart:html';
 import 'dart:js_util' as js_util;
 
@@ -50,7 +50,7 @@
 `callConstructor`. For example, instead of using the factory constructor for
 `KeyboardEvent`, we can do the following:
 
-```
+```dart
 import 'dart:html';
 import 'dart:js_util' as js_util;
 
@@ -77,7 +77,7 @@
 again to circumvent this issue. For example, we can manipulate a
 `_SubtleCrypto` object:
 
-```
+```dart
 import 'dart:html';
 import 'dart:js_util' as js_util;
 import 'dart:typed_data';
@@ -99,7 +99,7 @@
 What you shouldn’t do is attempt to cast these native objects using your own JS
 interop types, e.g.
 
-```
+```dart
 import 'dart:html';
 
 import 'package:js/js.dart';