JavaFX WebView reloads causing JVM crash.

Crashes have been observed since JDK 8u60 and are still present in the latest 8u72 builds.

Reproducible using JavaFX demo, WebViewSample.jar, found in
https://docs.oracle.com/javase/8/javafx/embedded-browser-tutorial/samples.htm.

Stack: [0x16740000,0x16790000], sp=0x1678e474, free space=313k
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native
code)
C [jfxwebkit.dll+0x702c4a]

Java frames: (J=compiled Java code, j=interpreted, Vv=VM code)
com.sun.webkit.network.URLLoader.twkWillSendRequest(Ljava/lang/String;Ljava/lang/String;ILjava/lang/String;Ljava/lang/String;JLjava/lang/String;Ljava/lang/String;J)Z+0
com.sun.webkit.network.URLLoader.notifyWillSendRequest(Ljava/lang/String;Ljava/lang/String;ILjava/lang/String;Ljava/lang/String;JLjava/lang/String;Ljava/lang/String;)Z+107
com.sun.webkit.network.URLLoader.lambda$willSendRequest$93(Ljava/lang/String;Ljava/lang/String;ILjava/lang/String;Ljava/lang/String;JLjava/lang/String;Ljava/lang/String;Ljava/util/concurrent/CountDownLatch;)V+21