Issue 5166: Auto-completion for CSS function parameters doesn't work correctly

No auto-completion, if nothing was entered

Steps to reproduce

1. Open Firebug
2. Switch to the HTML panel and there to the Style side panel
3. Inspect the blue <div> above
4. Inside the Style side panel select 135deg of the background property of the #element1 rule
   ⇒ The inline editor appears having 135deg selected
5. Press Del to remove 135deg
6. Press Down

Observed Result

• The auto-completion doesn't work.

Expected Result

• The Auto-completion should show top (or another completion value)

Wrong auto-completion for different parameters

Steps to reproduce

1. Open Firebug
2. Switch to the HTML panel and there to the Style side panel
3. Inspect the blue <div> above
4. Inside the Style side panel select #788CFF of the background property of the #element1 rule
   ⇒ The inline editor appears having #788CFF selected
5. Press Del to remove #788CFF
6. Type t

Observed Result

• The auto-completion completes to top.

Expected Result

• The auto-completion should just use completions, that are valid for the current parameter (in this case it should complete to tan)