Revert "Make all references from root shortcuts (except one to GC roots)"

This reverts commit 940418d2e1150499a28cca60b5dd138d351ec652. It resulted in orphan (Document DOM trees) and (Detached DOM trees) nodes.

BUG=chromium:414190
LOG=N
TBR=loislo@chromium.org, yangguo@chromium.org

Review URL: https://codereview.chromium.org/639753007

Cr-Commit-Position: refs/heads/master@{#24903}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24903 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
[turbofan] reduce allocations outside of pipeline

BUG=
R=bmeurer@chromium.org

Review URL: https://codereview.chromium.org/679793003

Cr-Commit-Position: refs/heads/master@{#24904}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24904 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Enable turbofan deoptimization by default.

BUG=
R=bmeurer@chromium.org

Review URL: https://codereview.chromium.org/638833004

Cr-Commit-Position: refs/heads/master@{#24905}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24905 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Remove unused return values from PreEdge visitor.

R=bmeurer@chromium.org

Review URL: https://codereview.chromium.org/679093002

Cr-Commit-Position: refs/heads/master@{#24906}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24906 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
SimpleMove now calls [[Has]] before [[Get]] when moving elements

BUG=v8:3643
LOG=n
R=mstarzinger@chromium.org

Review URL: https://codereview.chromium.org/678753002

Cr-Commit-Position: refs/heads/master@{#24907}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24907 ce2b1a6d-e550-0410-aec6-3dcde31c8c00