Use LLDB in gypv8sh to debug random crashes.

tools/gypv8sh.py

Index: tools/gypv8sh.py
diff --git a/tools/gypv8sh.py b/tools/gypv8sh.py
index ad6fa4a36328c24e7e7dc5df1b165fb773c395d4..8e8fd59fb1a27a3080636da580bbf84fb845607a 100755
--- a/tools/gypv8sh.py
+++ b/tools/gypv8sh.py
@@ -50,12 +50,38 @@ def main ():
       if p.returncode:
         # TODO(jochen): Remove once crbug.com/370551 is resolved.
         if sys.platform == 'darwin':
-          cmd[:0] = ['gdb', '-batch', '-ex', 'run', '-ex', 'bt', '-ex', 'quit',
-                     '-args']
-          p = subprocess.Popen(
-              cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE, bufsize=0)
-          out, err = p.communicate()
-        raise Exception('Failed to run d8', out, err)
+          sys.path.insert(0, '/Developer/Library/PrivateFrameworks/'
+                             'LLDB.framework/Resources/Python')
+          try:
+            import lldb
+          except:
+            raise Exception("Could not load lldb module")
+          debugger = lldb.SBDebugger.Create()
+          debugger.SetAsync(False)
+          target = debugger.CreateTargetWithFileAndArch(
+              cmd[0], lldb.LLDB_ARCH_DEFAULT)
+          if not target:
+            raise Exception("Failed to create d8 target")
+          process = target.LaunchSimple(cmd[1:], None, os.getcwd())
+          if not process:
+            raise Exception("Failed to start d8")
+          if process.GetState() == lldb.eStateStopped:
+            for thread in process:
+              print "Thread (id %d)" % thread.GetThreadID()
+              for frame in thread:
+                print frame
+              print ""
+            raise Exception(
+                "d8 crashed, please report this at http://crbug.com/370551")
+          else:
+            # For some reason d8 worked this time...
+            out = ''
+            while True:
+              s = process.GetSTDOUT(4096)
+              if s == '':
+                break
+              out += s
+
       with open(cxxoutfile, 'wb') as f:
         f.write(out)
       shutil.copyfile(inputfile, jsoutfile)