Split collections flag into weak and non-weak.

R=mstarzinger@chromium.org
BUG=

Review URL: https://codereview.chromium.org/201593004

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@20019 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

This re-re-re-lands enabling Object.observe. The Chromium tests that
failed last time this was rolled into Chromium have been disabled in
https://src.chromium.org/viewvc/chrome?view=revision&revision=256706

This patch should be safe to merge once that lands.

BUG=v8:2409
LOG=Y
TBR=rossberg@chromium.org,dslomov@chromium.org,rafaelw@chromium.org

Review URL: https://codereview.chromium.org/198383002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@19868 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

This reverts commit r19734 for breeaking ChromiumOS browser tests.
'OpenSpecialTypes/FileManagerBrowserTest.Test/3' started to time out,
bisecting the roll led to this change.
http://build.chromium.org/p/chromium.chromiumos/builders/Linux%20ChromiumOS%20Tests%20%282%29/builds/22224

TBR=rafaelw@chromium.org,rossberg@chromium.org
BUG=v8:2409
LOG=Y

Review URL: https://codereview.chromium.org/195123005

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@19816 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

Original Issue: https://codereview.chromium.org/183683022/

TBR=rossberg
BUG=v8:2409
LOG=Y

Review URL: https://codereview.chromium.org/189513010

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@19736 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

TBR=rossberg
BUG=

Review URL: https://codereview.chromium.org/190853007

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@19735 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

R=rossberg@chromium.org, rossberg
BUG=v8:2409
LOG=Y

Review URL: https://codereview.chromium.org/183683022

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@19734 ce2b1a6d-e550-0410-aec6-3dcde31c8c00