Theme the text colors of
- the debugger's log window
- the debugger's watch items

In particular, the watch items were hard to read (default color was
black, color for changed value was red).

For the dark theme, the default color for watch items is now white
(the text color), changed items appear red, and invalid items
appear grey.

Change-Id: I7f9534b054c44d635b106fa0e9ac70479c9fcac5
Reviewed-by: Orgad Shaneh <orgads@gmail.com>