FULL PRODUCT VERSION :
java version "1.8.0_60"
Java(TM) SE Runtime Environment (build 1.8.0_60-b27)
Java HotSpot(TM) Client VM (build 25.60-b23, mixed mode)

ADDITIONAL OS VERSION INFORMATION :
Window 7

A DESCRIPTION OF THE PROBLEM :
NullPointerException during layout when WebView width is over 8500.
This happens at least when WebView is inside a group.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Just run the sample application below and change the PrefWidth.
Over 8500 pixel, WebView crash
Below 800 pixel, it does'nt.


ERROR MESSAGES/STACK TRACES THAT OCCUR :
Executing D:\home\dev\JavaFxExamples\HtmlEditor\dist\run440091430\HtmlEditorSample.jar using platform C:\Program Files (x86)\Java\jdk1.8.0_60\jre/bin/java
java.lang.NullPointerException
at com.sun.javafx.webkit.prism.WCPageBackBufferImpl.validate(WCPageBackBufferImpl.java:97)
at com.sun.webkit.WebPage.paint(WebPage.java:656)
at com.sun.javafx.sg.prism.web.NGWebView.renderContent(NGWebView.java:96)
at com.sun.javafx.sg.prism.NGNode.doRender(NGNode.java:2053)
at com.sun.javafx.sg.prism.NGNode.render(NGNode.java:1945)
at com.sun.javafx.sg.prism.NGGroup.renderContent(NGGroup.java:235)
at com.sun.javafx.sg.prism.NGNode.doRender(NGNode.java:2053)
at com.sun.javafx.sg.prism.NGNode.render(NGNode.java:1945)
at com.sun.javafx.tk.quantum.ViewPainter.doPaint(ViewPainter.java:477)
at com.sun.javafx.tk.quantum.ViewPainter.paintImpl(ViewPainter.java:330)
at com.sun.javafx.tk.quantum.PresentingPainter.run(PresentingPainter.java:91)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:308)
at com.sun.javafx.tk.RenderJob.run(RenderJob.java:58)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at com.sun.javafx.tk.quantum.QuantumRenderer$PipelineRunnable.run(QuantumRenderer.java:125)
at java.lang.Thread.run(Thread.java:745)

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
import javafx.application.Application;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.web.WebView;
import javafx.stage.Stage;

public class WebViewCrashIfTooLarge extends Application {

    @Override
    public void start(Stage stage) throws InterruptedException {
        stage.setTitle("WebView crash if size is too large");
        stage.setWidth(500);
        stage.setHeight(500);
        final WebView webView = new WebView();
        webView.setPrefWidth(9000);
        Group group = new Group(webView);
        stage.setScene(new Scene(group));
        stage.show();
    }
}
---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
set the maxWidth and maxHeight of the webView seems a good by pass :

     sceneProperty().addListener(new ChangeListener<Scene>() {

            @Override
            public void changed(ObservableValue<? extends Scene> observable, Scene oldValue, Scene scene) {
                if (scene != null) {
                    webView.setMaxSize(getScene().getWidth(), getScene().getHeight());
                    webView.maxWidthProperty().bind(getScene().widthProperty());
                    webView.maxHeightProperty().bind(getScene().heightProperty());
                } else {
                    webView.maxWidthProperty().unbind();
                    webView.maxHeightProperty().unbind();
                }
            }
        });