Revert "Roll SwiftShader 88482c3..700a1a6"

This reverts commit 083b6f26.

Reason for revert: I think this is causing crashes on Mac 10.13 (dbg). See https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/Mac10.13%20Tests%20%28dbg%29/3362.

Original change's description:
> Roll SwiftShader 88482c3..700a1a6
> 
> https://swiftshader.googlesource.com/SwiftShader.git/+log/88482c3..700a1a6
> 
> BUG=chromium:845700, chromium:852641, chromium:851707
> 
> TBR=kbr@chromium.org
> 
> TEST=bots
> 
> CQ_INCLUDE_TRYBOTS=luci.chromium.try:win_optional_gpu_tests_rel;luci.chromium.try:mac_optional_gpu_tests_rel;luci.chromium.try:linux_optional_gpu_tests_rel;master.tryserver.chromium.linux:linux_chromium_cfi_rel_ng;luci.chromium.try:android_optional_gpu_tests_rel
> 
> Change-Id: Ic36ddc1988cd83970a4a53b52a1ce1b229d17137
> Reviewed-on: https://chromium-review.googlesource.com/1102886
> Commit-Queue: Nicolas Capens <capn@chromium.org>
> Reviewed-by: Alexis Hétu <sugoi@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#567894}

TBR=sugoi@chromium.org,capn@chromium.org

Change-Id: I96e96329f4de1581ca11fca443fa943e58ce8f4c
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: chromium:845700, chromium:852641, chromium:851707
Cq-Include-Trybots: luci.chromium.try:win_optional_gpu_tests_rel;luci.chromium.try:mac_optional_gpu_tests_rel;luci.chromium.try:linux_optional_gpu_tests_rel;master.tryserver.chromium.linux:linux_chromium_cfi_rel_ng;luci.chromium.try:android_optional_gpu_tests_rel
Reviewed-on: https://chromium-review.googlesource.com/1103398Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Commit-Queue: Dirk Pranke <dpranke@chromium.org>
Cr-Commit-Position: refs/heads/master@{#567898}

DEPS

@@ -125,7 +125,7 @@ vars = {
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling SwiftShader
   # and whatever else without interference from each other.
-  'swiftshader_revision': '700a1a67d569fd5a4960ec36fce9c35d2b59aca2',
+  'swiftshader_revision': '88482c3ca96642733b3a4cc3566b7e2d1b5f8025',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling PDFium
   # and whatever else without interference from each other.