Bug 1585635 [wpt PR 19463] - Update interfaces/media-capabilities.idl, a=testonly

Automatic update from web-platform-tests
Update interfaces/media-capabilities.idl (#19463)

Source: https://github.com/tidoust/reffy-reports/blob/3ae3130/ed/idl/media-capabilities.idl
Build: https://travis-ci.org/tidoust/reffy-reports/builds/592538394
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wpt-commits: 3c62b4e788a0f5e91a620cd2b97c14d4b64d9182
wpt-pr: 19463

testing/web-platform/tests/interfaces/media-capabilities.idl

@@ -32,7 +32,7 @@ dictionary VideoConfiguration {
   required unsigned long width;
   required unsigned long height;
   required unsigned long long bitrate;
-  required DOMString framerate;
+  required double framerate;
   boolean hasAlphaChannel;
 };