make interpreter fully preemptive

context.js

@@ -150,7 +150,7 @@ Context.prototype.newString = function(s) {
   return obj;
 }
 
-Context.prototype.run = function(stopFrame) {
+Context.prototype.execute = function(stopFrame) {
   while (this.current() !== stopFrame) {
     try {
       VM.execute(this);
@@ -160,3 +160,18 @@ Context.prototype.run = function(stopFrame) {
     }
   }
 }
+
+Context.prototype.start = function(stopFrame) {
+  if (this.current() === stopFrame)
+    return;
+  var ctx = this;
+  window.setZeroTimeout(function() {
+    try {
+      VM.execute(ctx);
+    } catch (e) {
+      if (e !== VM.Yield)
+        throw e;
+    }
+    ctx.start(stopFrame);
+  });
+}

jvm.js

@@ -42,15 +42,15 @@ JVM.prototype.run = function(className) {
 
     ["java/lang/Object", "java/lang/String", "java/lang/Class", "java/lang/Thread"].forEach(function(className) {
         ctx.pushClassInitFrame(CLASSES[className.replace("/", "_", "g")] = CLASSES.loadClass(className));
-        ctx.run(caller);
+        ctx.execute(caller);
     });
 
     ctx.thread = CLASSES.mainThread = CLASSES.newObject(CLASSES.java_lang_Thread);
     caller.stack.push(CLASSES.mainThread);
     caller.stack.push(ctx.newString("main"));
     ctx.pushFrame(CLASSES.getMethod(CLASSES.java_lang_Thread, "<init>", "(Ljava/lang/String;)V"), 2);
-    ctx.run(caller);
+    ctx.execute(caller);
     caller.stack.push(CLASSES.newArray("[Ljava/lang/String;", 0));
     ctx.pushFrame(entryPoint, 1);
-    ctx.run(caller);
+    ctx.start(caller);
 }

native.js

@@ -231,7 +231,7 @@ Native["java/lang/Thread.start0.()V"] = function(ctx, stack) {
         caller.stack.push(thread);
         ctx.frames.push(caller);
         ctx.pushFrame(run, 1);
-        ctx.run(caller);
+        ctx.start(caller);
     });
 }