Clarify units for timeout

sdk/lib/html/dartium/html_dartium.dart

Index: sdk/lib/html/dartium/html_dartium.dart
diff --git a/sdk/lib/html/dartium/html_dartium.dart b/sdk/lib/html/dartium/html_dartium.dart
index 77a2613ceac513bffebcbfeeec8c80577c381316..6c06c5a4944f40a1d495418973465d0388e9e49c 100644
--- a/sdk/lib/html/dartium/html_dartium.dart
+++ b/sdk/lib/html/dartium/html_dartium.dart
@@ -22569,7 +22569,8 @@ class HttpRequest extends HttpRequestEventTarget {
       _blink.BlinkXMLHttpRequest.instance.statusText_Getter_(this);
 
   /**
-   * Length of time before a request is automatically terminated.
+   * Length of time in milliseconds before a request is automatically
+   * terminated.
    *
    * When the time has passed, a [TimeoutEvent] is dispatched.
    *
@@ -22588,7 +22589,8 @@ class HttpRequest extends HttpRequestEventTarget {
   int get timeout => _blink.BlinkXMLHttpRequest.instance.timeout_Getter_(this);
 
   /**
-   * Length of time before a request is automatically terminated.
+   * Length of time in milliseconds before a request is automatically
+   * terminated.
    *
    * When the time has passed, a [TimeoutEvent] is dispatched.
    *