WebKit 620.1 crashes on startup when running a 32-bit binary on Windows. This can be reproduced running HelloWebView with any .html file. For example:

$ java HelloWebView file:///C:/path/to/simple.html

#
# A fatal error has been detected by the Java Runtime Environment:
#
# EXCEPTION_ACCESS_VIOLATION (0xc0000005) at pc=0x1bc905e8, pid=19932, tid=0x000094b4
#
# JRE version: Java(TM) SE Runtime Environment (8.0) (build 1.8.0_451-b06)
# Java VM: Java HotSpot(TM) Client VM (25.451-b06 mixed mode windows-x86 )
# Problematic frame:
# C [jfxwebkit.dll+0xe505e8]
#
# Failed to write core dump. Minidumps are not enabled by default on client versions of Windows
#
# An error report file with more information is saved as:
# C:\Users\kcr\dev\javafx\tmp\hs_err_pid19932.log
#
# If you would like to submit a bug report, please visit:
# http://bugreport.java.com/bugreport/crash.jsp
# The crash happened outside the Java Virtual Machine in native code.
# See problematic frame for where to report the bug.
#

I'll attach a log file.

NOTE: The JDK 8 certified configurations page recommends against running WebKit using 32-bit binaries (due to other known problems).