gclient: remove support for From() (reland #1)

Original CL: https://chromium-review.googlesource.com/509693

This feature appears unused, and removing it will simplify the codebase.

Bug: 661382
Change-Id: I0d83b537b57d0b9ca65c7101d13e0ad6c1642a29
Reviewed-on: https://chromium-review.googlesource.com/512842
Reviewed-by: Andrii Shyshkalov <tandrii@chromium.org>
Commit-Queue: Paweł Hajdan Jr. <phajdan.jr@chromium.org>
diff --git a/gclient_utils.py b/gclient_utils.py
index d46dbd1..8fe0c5e 100644
--- a/gclient_utils.py
+++ b/gclient_utils.py
@@ -813,8 +813,7 @@
   """Runs a set of WorkItem that have interdependencies and were WorkItem are
   added as they are processed.
 
-  In gclient's case, Dependencies sometime needs to be run out of order due to
-  From() keyword. This class manages that all the required dependencies are run
+  This class manages that all the required dependencies are run
   before running each one.
 
   Methods of this class are thread safe.