text: // After returning from an implicit toString call, the calling frame's onStep
  // hook fires.
  
  var g = newGlobal();
  g.eval("var originalX = {toString: function () { debugger; log += 'x'; return 1; }};\n");
  
  var dbg = Debugger(g);
  dbg.onDebuggerStatement = function (frame) {
      g.log += 'd';
      frame.older.onStep = function () {
          if (!g.log.match(/[sy]$/))
              g.log += 's';
      };
  };
  
  // expr is an expression that will trigger an implicit toString call.
  function check(expr) {
      g.log = '';
      g.x = g.originalX;
      g.eval(expr + ";\n" +
  	   "log += 'y';\n");
      assertEq(g.log, 'dxsy');
  }
  
  check("'' + x");
  check("0 + x");
  check("0 - x");
  check("0 * x");
  check("0 / x");
  check("0 % x");
  check("+x");
  check("x in {}");
  check("x++");
  check("++x");
  check("x--");
  check("--x");
  check("x < 0");
  check("x > 0");
  check("x >= 0");
  check("x <= 0");
  check("x == 0");
  check("x != 0");
  check("x & 1");
  check("x | 1");
  check("x ^ 1");
  check("~x");
  check("x << 1");
  check("x >> 1");
  check("x >>> 1");
  
  g.eval("function lastStep() { throw StopIteration; }");
  g.eval("function emptyIterator() { debugger; log += 'x'; return { next: lastStep }; }");
  g.eval("var customEmptyIterator = { __iterator__: emptyIterator };");
  g.log = '';
  g.eval("for (i in customEmptyIterator);\n" +
         "log += 'y';\n");
  assertEq(g.log, 'dxsy');
  
  g.eval("var getter = { get x() { debugger; return log += 'x'; } }");
  check("getter.x");
  
  g.eval("var setter = { set x(v) { debugger; return log += 'x'; } }");
  check("setter.x = 1");
  
  g.eval("Object.defineProperty(this, 'thisgetter', { get: function() { debugger; log += 'x'; }});");
  check("thisgetter");
  