Revert 245737 "Reenable linux_aura on the main builders. (Again)."

build/common.gypi

Index: build/common.gypi
===================================================================
--- build/common.gypi	(revision 251945)
+++ build/common.gypi	(working copy)
@@ -81,14 +81,6 @@
               'use_aura%': 1,
             }],
 
-            # ToT Linux should be aura.
-            #
-            # TODO(erg): Merge this into the previous block once compiling with
-            # aura safely implies including ash capabilities.
-            ['OS=="linux"', {
-              'use_aura%': 1,
-            }],
-
             # Whether we're a traditional desktop unix.
             ['(OS=="linux" or OS=="freebsd" or OS=="openbsd" or OS=="solaris") and chromeos==0', {
               'desktop_linux%': 1,