Dial back on host-checked testing.

dart/tools/bots/compiler.py

Index: dart/tools/bots/compiler.py
diff --git a/dart/tools/bots/compiler.py b/dart/tools/bots/compiler.py
index ed93147e83b3f818a00da34ac80a5f59f1a7de39..3de5b935e212507a38d16c6117bdbfb82ee3e678 100644
--- a/dart/tools/bots/compiler.py
+++ b/dart/tools/bots/compiler.py
@@ -222,9 +222,13 @@ def TestCompiler(runtime, mode, system, flags, is_buildbot, test_set):
 
     # TODO(kasperl): Consider running peg and css tests too.
     extras = ['dart2js_extra', 'dart2js_native', 'dart2js_foreign']
+    extras_flags = flags
+    if system == 'linux' and runtime == 'd8':
+      # Run the extra tests in checked mode, but only on linux/d8.
+      # Other systems have less resources and tend to time out.
+      extras_flags = extras_flags + ['--host-checked']
     TestStep("dart2js_extra", mode, system, 'dart2js', runtime, extras,
-             # Run this small test subset in checked mode.
-             flags + ['--host-checked'])
+             extras_flags)
 
 
 def _DeleteTempWebdriverProfiles(directory):