[wasm] Implement stepping in wasm code

src/debug/debug.js

Index: src/debug/debug.js
diff --git a/src/debug/debug.js b/src/debug/debug.js
index 512bedb69fbffd0788ad3ea3180695653f77c6d5..7cb5fda95c5e95437eafea828e5c9608f58450d9 100644
--- a/src/debug/debug.js
+++ b/src/debug/debug.js
@@ -1293,13 +1293,12 @@ DebugCommandProcessor.prototype.processDebugJSONRequest = function(
 DebugCommandProcessor.prototype.continueRequest_ = function(request, response) {
   // Check for arguments for continue.
   if (request.arguments) {
-    var action = Debug.StepAction.StepIn;
-
     // Pull out arguments.
     var stepaction = request.arguments.stepaction;
 
     // Get the stepaction argument.
     if (stepaction) {

[titzer, 2017/01/23 10:10:10]

This can probably be further simplified to just be a switch with a default case,
and no if.

[Clemens Hammacher, 2017/01/23 12:25:34]

Yang just removed this whole code anyway :)

+      var action;
       if (stepaction == 'in') {
         action = Debug.StepAction.StepIn;
       } else if (stepaction == 'next') {
@@ -1310,10 +1309,10 @@ DebugCommandProcessor.prototype.continueRequest_ = function(request, response) {
         throw %make_error(kDebugger,
                         'Invalid stepaction argument "' + stepaction + '".');
       }
-    }
 
-    // Set up the VM for stepping.
-    this.exec_state_.prepareStep(action);
+      // Set up the VM for stepping.
+      this.exec_state_.prepareStep(action);
+    }
   }
 
   // VM should be running after executing this request.