Bug 1096704 - Prevent rocketbar trigger during an edge gesture.

(cherry picked from commit 4d4f7b91c958f6cee8a13a4fe43c25840c142911)
Merge pull request #26248 from etiennesegonzac/bug-1096704

Bug 1096704 - Prevent rocketbar trigger during an edge gesture. r=alive, aus