When using the "Alt-Enter" shortcut with a breakpoint selected, the
properties dialog that is created is missing some fields. This seems to
be caused by the fact that the dialog, when summoned in this way, is
created using a wrong context: an ICLineBreakpoint instead of the
expected CBreakpointContext. That context is then used to fetch
properties from the store, which fails.
This is a naive fix that attempts to work around this by creating a
proper context from the breakpoint.
Change-Id: I2b7c86965d09898dd1cd7eeb3c3f704bb2995e20