How to change key-bindings in firefox?

Firefox constantly keep moving platformHTMLBindings.xml when it upgrade.
I want to replace it to support vi key-bindings. But I cannot find it any more.

sudo find / -name platformHTMLBindings.xml -o -name toolkit.jar -o -name omni.jar

Thanks for your help.

Edit:

I finally found it. It's called omni.ja now.

This is my editing to platformHTMLBindings.xml:

  <binding id="browser">
    <handlers>
      <handler event="keypress" key=" " modifiers="shift" command="cmd_scrollPageUp" />
      <handler event="keypress" key=" " command="cmd_scrollPageDown" />

      <handler event="keypress" key="k" command="cmd_scrollLineUp" />
      <handler event="keypress" key="j" command="cmd_scrollLineDown" />
      <handler event="keypress" key="h" command="cmd_scrollLeft" />
      <handler event="keypress" key="l" command="cmd_scrollRight" />

After Editing, I restart firefox, and clear the cache.
chrome://global/content/platformHTMLBindings.xml is correct.
But the j/k/h/l shortcuts didn't work.