Allow file prompt type (#1884)

* Allow `fileUpload` prompt type

* Rename to `fileDialog`

* Rename to `file`

Author: sadym-chromium

index.html

@@ -10481,7 +10481,7 @@ <h3>User Prompt Handler</h3>
 
 <p>The <dfn>valid prompt types</dfn> are «"<code>alert</code>",
 "<code>beforeUnload</code>", "<code>confirm</code>",
-"<code>default</code>", "<code>prompt</code>"».
+"<code>default</code>", "<code>file</code>", "<code>prompt</code>"».
 
 <p class="note">The "<code>default</code>" type represents a fallback
 when no specific handler is defined for a given prompt type, including
@@ -10497,6 +10497,9 @@ <h3>User Prompt Handler</h3>
 other protocols isn&apos;t expected to change the user prompt handling as a
 side effect.
 
+<p class="note">The "<code>file</code>" prompt type is respected only in
+[[WebDriver-BiDi]] sessions.
+
 <p>To <dfn>deserialize as an unhandled prompt behavior</dfn> given
 argument <var>value</var>: