ImageHelper object is not refcounted and garbage collected and
endRenderPass call is deferred until next render pass starts. This
caused a situation that an ImageHelper object gets deleted while still
referenced in the open render pass. This CL make sure that we call into
all shared context's open renderpass when an image goes away so that
they can take appropriate action for this.

Bug: b/169618408
Change-Id: I5075e805980084db82ca3e699462272eee5d2d59
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2443571Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Tim Van Patten <timvp@google.com>
Commit-Queue: Charlie Lao <cclao@google.com>