Revert of Add support for escaped target names in isolate driver (4th try)

tools/isolate_driver.py

Index: tools/isolate_driver.py
diff --git a/tools/isolate_driver.py b/tools/isolate_driver.py
index f51b824cb63e75b58f0f91d1b69dd11dc17b7963..6c9f11886633c1343297e885204e50cbb3560fa2 100755
--- a/tools/isolate_driver.py
+++ b/tools/isolate_driver.py
@@ -24,7 +24,6 @@
 import logging
 import os
 import posixpath
-import re
 import StringIO
 import subprocess
 import sys
@@ -142,9 +141,7 @@
   # TODO(maruel): Use a whitelist instead? .stamp, .so.TOC, .dylib.TOC,
   # .dll.lib, .exe and empty.
   # The first item is the build rule, e.g. 'link', 'cxx', 'phony', etc.
-  # In ninja build files, spaces in targets are escaped with a $-prefix.
-  # Use a negative lookbehind to not split on '$ '.
-  return filter(using_blacklist, re.split('(?<!\$) ', item)[1:])
+  return filter(using_blacklist, item.split(' ')[1:])
 
 
 def collect_deps(target, build_steps, dependencies_added, rules_seen):