8240969: WebView does not allow to load style sheet in modularized applications

modules/javafx.web/src/main/java/javafx/scene/web/WebEngine.java

@@ -491,7 +491,7 @@ public final BooleanProperty javaScriptEnabledProperty() {
      * Location of the user stylesheet as a string URL.
      *
      * <p>This should be a local URL, i.e. either {@code 'data:'},
-     * {@code 'file:'}, or {@code 'jar:'}. Remote URLs are not allowed
+     * {@code 'file:'}, {@code 'jar:'}, or {@code 'jrt:'}. Remote URLs are not allowed
      * for security reasons.
      *
      * @defaultValue null
@@ -554,6 +554,7 @@ public final StringProperty userStyleSheetLocationProperty() {
                         dataUrl = url;
                     } else if (url.startsWith("file:") ||
                                url.startsWith("jar:")  ||
+                               url.startsWith("jrt:")  ||
                                url.startsWith("data:"))
                     {
                         try {

modules/javafx.web/src/test/java/test/javafx/scene/web/MiscellaneousTest.java

@@ -473,4 +473,18 @@ void waitForCompletion() {
             assertNull(getEngine().executeScript("window.xmlDoc.body"));
         });
     }
+
+    @Test public void jrtCssFileIsNotRejected() {
+        submit(() -> {
+            try {
+                getEngine().setUserStyleSheetLocation("jrt:/javafx.web/html/imported-styles.css");
+            } catch (IllegalArgumentException e) {
+                // A jrt file is supposed to be a valid argument
+                throw new AssertionError(e);
+            } catch (RuntimeException e) {
+                // The css file cannot be loaded in the tests (since they are not modularized).
+                // We thus simply ignore this exception here
+            }
+        });
+    }
 }