Modal pop-up persists when a breakpoint cannot resolve conditional expression

[cwebster-99]

Sometimes when a conditional breakpoints is set with values the debugger cannot resolve the conditional expression, a modal pop-up is presented with details, but then if the breakpoint is being continuously hit, this modal pop-up keeps being presented and it's impossible to stop debugging or even exit Visual Studio and it has to be killed via Task Manager.

[cwebster-99]

Ref https://github.com/microsoft/PTVS/issues/7594