Fix percent height calc for svg docs.

third_party/WebKit/Source/platform/RuntimeEnabledFeatures.json5

 {
   // http://dev.chromium.org/blink/runtime-enabled-features
   //
   // This list is used to generate RuntimeEnabledFeatures.h/cpp which contains
   // a class that stores static enablers for all experimental features.
 
   parameters: {
     // Each feature can be assigned a "status":
     // status=stable -> Enable this in all Blink configurations.  We are committed to these APIs indefinitely.
     // status=experimental -> In-progress features, Web Developers might play with, but are not on by default in stable.
@@ skipping 678 matching lines @@
     // Define a sample API for testing integration with the Origin Trials Framework.
     // The sample API is used in both unit and layout tests for the Origin Trials
     // Framework. Do not change this flag to stable, as it exists solely to generate
     // code used by the sample API implementation.
     {
       name: "OriginTrialsSampleAPI",
       origin_trial_feature_name: "Frobulate",
     },
     {
       name: "OverlayScrollbars",
+      settable_from_internals: true,
     },
     {
       name: "PagePopup",
       status: "stable",
     },
     {
       name: "PaintUnderInvalidationChecking",
       settable_from_internals: true,
     },
     {
@@ skipping 348 matching lines @@
     {
       name: "Worklet",
       status: "experimental",
     },
     {
       name: "XSLT",
       status: "stable",
     },
   ],
 }