Conditional breakpoint can not be restored after restart and breaks debug UI

[kieferrm]

While testing #12600.

• VSCode Version: 1.6.0 insiders
• OS Version: MacOs

Steps to Reproduce:

1. open a workspace
2. open a js file
3. set breakpoint
4. edit the breakpoint to be conditional
5. quit vscode
6. restart vscode
   -> editor on file as in step 2 opens; no breakpoint It creates the stack trace below
   -> When ups now debug the debugger still stops at the breakpoint but the yellow 'current execution point' indication gets stuck at the conditional break point. I.e. the debugging UI is broken.

shell.ts:441Cannot read property 'model' of undefined: TypeError: Cannot read property 'model' of undefined
    at e.getBreakpointDecorationOptions (file:////***/Visual Studio Code - Insiders.app/Contents/Resources/app/out/vs/workbench/workbench.main.js:82:14496)
    at file:////***/Visual Studio Code - Insiders.app/Contents/Resources/app/out/vs/workbench/workbench.main.js:82:13777
    at Array.map (native)
    at e.createBreakpointDecorations (file:////***/Visual Studio Code - Insiders.app/Contents/Resources/app/out/vs/workbench/workbench.main.js:82:13744)
    at e.onModelAdded (file:////***/Visual Studio Code - Insiders.app/Contents/Resources/app/out/vs/workbench/workbench.main.js:82:10069)
    at e.invoke (file:////***/Visual Studio Code - Insiders.app/Contents/Resources/app/out/vs/workbench/workbench.main.js:29:20764)
    at e.fire (file:////***/Visual Studio Code - Insiders.app/Contents/Resources/app/out/vs/workbench/workbench.main.js:29:31336)
    at e.createModel (file:////***/Visual Studio Code - Insiders.app/Contents/Resources/app/out/vs/workbench/workbench.main.js:69:21524)
    at t.doCreateTextEditorModel (file:////***/Visual Studio Code - Insiders.app/Contents/Resources/app/out/vs/workbench/workbench.main.js:80:13509)
    at file:////***/Visual Studio Code - Insiders.app/Contents/Resources/app/out/vs/workbench/workbench.main.js:80:13263e.onUnexpectedError @ shell.ts:441