crash on windows7

[iriswe]

The 'webview_cef/23159' channel sent a message from native to Flutter on a non-platform thread. Platform channel messages must be sent on the platform thread. Failure to do so may result in data loss or crashes, and must be fixed in the plugin or application code creating that channel

[SinyimZhi]

@iriswe cef run in another thread on windows to build it's own message loop, and flutter did't afford api which can send message to main thread on windows.There are two ways to solve this problem:1.build message poster and handler for this plugin on native side.2.let flutter main thread proxy cef's message loop like linux and macos.This issue may not be resolved in a short period of time, but it will be addressed.

[SinyimZhi]

@iriswe I've tryed invoke method to flutter on platform thread by windows message loop. Cause we don't have windows 7. Can you help us do some tests?