Implement unregisterProtocolHandler() function on CUSTOM_SCHEME_HANDLER

Source/web/WebRuntimeFeatures.cpp

Index: Source/web/WebRuntimeFeatures.cpp
diff --git a/Source/web/WebRuntimeFeatures.cpp b/Source/web/WebRuntimeFeatures.cpp
index 312ebce0810370cc16c486aee2c197c2a45e29d8..903795ed0f57a4a348fcb7e4046d97673e995cc7 100644
--- a/Source/web/WebRuntimeFeatures.cpp
+++ b/Source/web/WebRuntimeFeatures.cpp
@@ -387,6 +387,22 @@ bool WebRuntimeFeatures::isHTMLImportsEnabled()
     return RuntimeEnabledFeatures::htmlImportsEnabled();
 }
 
+void WebRuntimeFeatures::enableCustomSchemeHandler(bool enable)
+{
+#if ENABLE(CUSTOM_SCHEME_HANDLER)
+    RuntimeEnabledFeatures::setCustomSchemeHandlerEnabled(enable);
+#endif
+}
+
+bool WebRuntimeFeatures::isCustomSchemeHandlerEnabled()
+{
+#if ENABLE(CUSTOM_SCHEME_HANDLER)
+    return RuntimeEnabledFeatures::customSchemeHandlerEnabled();
+#else
+    return false;
+#endif
+}
+
 // FIXME: Remove this when embedders switch to enableEmbedderCustomElements.
 void WebRuntimeFeatures::enableCustomElements(bool enable)
 {