Reapply "debug: Wait 50ms before running the main module"

This reapplies commit c781f17742
This reverts commit 00224771e3

src/node.js

@@ -89,10 +89,31 @@
       }
 
       var Module = NativeModule.require('module');
-      // REMOVEME: nextTick should not be necessary. This hack to get
-      // test/simple/test-exception-handler2.js working.
-      // Main entry point into most programs:
-      process.nextTick(Module.runMain);
+
+      if (global.v8debug &&
+          process.execArgv.some(function(arg) {
+            return arg.match(/^--debug-brk(=[0-9]*)?$/);
+          })) {
+
+        // XXX Fix this terrible hack!
+        //
+        // Give the client program a few ticks to connect.
+        // Otherwise, there's a race condition where `node debug foo.js`
+        // will not be able to connect in time to catch the first
+        // breakpoint message on line 1.
+        //
+        // A better fix would be to somehow get a message from the
+        // global.v8debug object about a connection, and runMain when
+        // that occurs.  --isaacs
+
+        setTimeout(Module.runMain, 50);
+
+      } else {
+        // REMOVEME: nextTick should not be necessary. This hack to get
+        // test/simple/test-exception-handler2.js working.
+        // Main entry point into most programs:
+        process.nextTick(Module.runMain);
+      }
 
     } else {
       var Module = NativeModule.require('module');