multiple javascript methods calls not invoked in expression
<p>The JavaScript function</p>

<pre><code>function tile(u,v, a,b,c,d) {
  var c0 = tileCorners[a].eval(u,v);
  var c1 = tileCorners[b].eval(u-1,v);
  var c2 = tileCorners[c].eval(u,v-1);
  var c3 = tileCorners[d].eval(u-1,v-1);
  return c0 + c1 + c2 + c3;
}
</code></pre>

<p>should be equivalent to</p>

<pre><code>function tile(u,v, a,b,c,d) {
  return
    tileCorners[a].eval(u,v) +
    tileCorners[b].eval(u-1,v) +
    tileCorners[c].eval(u,v-1) +
    tileCorners[d].eval(u-1,v-1);
}
</code></pre>

<p>yet the second function always returns <code>undefined</code> (the debugger will not "step into" the calls to <code>eval</code>) whereas the first function behaves correctly.
Is there something about having multiple <code>eval</code> method calls in an expression that is wrong?</p>
