Revert of Move (hopefully) remaining isolate related variables to toolchain.gypi

gypfiles/standalone.gypi

Index: gypfiles/standalone.gypi
diff --git a/gypfiles/standalone.gypi b/gypfiles/standalone.gypi
index 3191641310d89670860a0079f7cbecf682b7442f..d764e80b1f567561541e8356a82370f60271a943 100644
--- a/gypfiles/standalone.gypi
+++ b/gypfiles/standalone.gypi
@@ -111,6 +111,9 @@
       # If no gomadir is set, it uses the default gomadir.
       'use_goma%': 0,
       'gomadir%': '',
+
+      # Check if valgrind directories are present.
+      'has_valgrind%': '<!pymod_do_main(has_valgrind)',
 
       'test_isolation_mode%': 'noop',
 
@@ -161,6 +164,7 @@
     'test_isolation_mode%': '<(test_isolation_mode)',
     'fastbuild%': '<(fastbuild)',
     'coverage%': '<(coverage)',
+    'has_valgrind%': '<(has_valgrind)',
 
     # Add a simple extras solely for the purpose of the cctests
     'v8_extra_library_files': ['../test/cctest/test-extra.js'],