Context isolation bypass in Electron

Electron before versions 11.0.0-beta.6, 10.1.2, 9.3.1 or 8.5.2 is vulnerable to a context isolation bypass. Apps using both `contextIsolation` and `sandbox: true` are affected. Apps using both `contextIsolation` and `nodeIntegrationInSubFrames: true` are affected. This is a context isolation bypass, meaning that code running in the main world context in the renderer can reach into the isolated Electron context and perform privileged actions.