Call stack missing type names on JS in Chrome

This seems like a significant oversight, so in addition to reporting this, I'm kinda hoping for a sanity check and maybe some additional historical context from anybody who knows (was this definitely tested before?).

When `haxe.CallStack.callStack()` is called on the javascript target with ES5 code generation, running in Chrome (or presumably anywhere that V8 is used), any `Method` stack item that comes from a static or abstract function call will include the type information, but those that come from function calls on an instance of a type will not.

Running the same when ES6 code generation is enabled is even worse. No type names at all are included.

try.haxe program: https://try.haxe.org/#98c971A4

```haxe
import js.lib.Error;

using StringTools;

class Test {
static function main() {
staticFunction();
}

static function staticFunction()
{
var abstractObject = new AbstractObject(new RealObject());
abstractObject.abstractFunction();
}
}

abstract AbstractObject(RealObject)
{
public function new(real:RealObject)
{
this = real;
}

public function abstractFunction()
{
this.instanceFunction();
}
}

class RealObject
{
public function new()
{

}

public function instanceFunction()
{
//js.Syntax.code("debugger");
var stack = haxe.CallStack.callStack();

for(stackItem in stack)
{
trace(stackItem);
}
/* ES5
Test.hx:44:,FilePos(Method(null,instanceFunction),_,_,_)
Test.hx:44:,FilePos(Method(AbstractObject,abstractFunction),_,_,_)
Test.hx:44:,FilePos(Method(Test,staticFunction),_,_,_)
Test.hx:44:,FilePos(Method(Test,main),_,_,_)
Test.hx:44:,FilePos(null,_,_,_)
Test.hx:44:,FilePos(null,_,_,_)
*/

/* ES6
Test.hx:44:,FilePos(Method(null,instanceFunction),_,_,_)
Test.hx:44:,FilePos(Method(null,abstractFunction),_,_,_)
Test.hx:44:,FilePos(Method(null,staticFunction),_,_,_)
Test.hx:44:,FilePos(Method(null,main),_,_,_)
Test.hx:44:,FilePos(null,_,_,_)
Test.hx:44:,FilePos(null,_,_,_)
*/
}
}
```

This is simple enough to fix in the standard library's javascript implementation of `NativeStackTrace.prepareHxStackTrace` for ES5 code. I have a commit prepared with a fix for that case (https://github.com/justin-espedal/haxe/commit/243c4d972b15b3d787700e25756c82adcf155748), but thought I'd withhold it pending discussion. For ES6 code I have no idea because `site.getTypeName()`, `site.getFunctionName()`, and `site.getMethodName()` all don't provide the needed information for static functions and abstracts.