Fixes bug 823041 (#870)
Fixes bug 823041 (#870)

When no documentContext is available when calling
IDebugCodeContext.GetDocumentContext() return S_FALSE instead.
orbitcowboy/MIEngine,Microsoft/MIEngine,Microsoft/MIEngine,Microsoft/MIEngine,Microsoft/MIEngine,orbitcowboy/MIEngine,orbitcowboy/MIEngine,orbitcowboy/MIEngine