Merge up to 8597 to experimental/gc from the bleeding edge.

tools/test.py

Index: tools/test.py
===================================================================
--- tools/test.py	(revision 8618)
+++ tools/test.py	(working copy)
@@ -1272,6 +1272,11 @@
       options.special_command += " --crankshaft"
     else:
       options.special_command = "@--crankshaft"
+  if options.shell == "d8":
+    if options.special_command:
+      options.special_command += " --test"
+    else:
+      options.special_command = "@--test"
   if options.noprof:
     options.scons_flags.append("prof=off")
     options.scons_flags.append("profilingsupport=off")
@@ -1437,7 +1442,8 @@
         'system': utils.GuessOS(),
         'arch': options.arch,
         'simulator': options.simulator,
-        'crankshaft': options.crankshaft
+        'crankshaft': options.crankshaft,
+        'isolates': options.isolates
       }
       test_list = root.ListTests([], path, context, mode, [])
       unclassified_tests += test_list