GC initial loading revision, fixing panic
GC initial loading revision, fixing panic

Fixes https://github.com/google/xi-mac/issues/52 by including the revision
that contains the initial contents in the GC call the Editor makes. The GC
only supports GCing prefixes of the visible edit history but when the initial
revision was introduced, the Editor no longer abided by that restriction,
causing invalid states and thus crashes.

fuchsia-mirror/third_party-xi-editor,modelorganism/xi-editor,fuchsia-mirror/third_party-xi-editor,modelorganism/xi-editor,google/xi-editor,google/xi-editor,google/xi-editor,fuchsia-mirror/third_party-xi-editor,fuchsia-mirror/third_party-xi-editor,google/xi-editor,modelorganism/xi-editor