Overridden to fix indentation problem with tabs.
If the original source code uses tabs, then the tokenizer
will see this as "1" indent level, and will indent new lines
with just 1 space. By changing 1 indent to 4, we effectively
"correct" this problem when printing.
For code that is even further indented (e.g. 8 spaces),
the printer uses the first indentation (here corrected
from 1 space to 4) and already (without needing any other
changes) adds 4 spaces onto that. This is why we don't
also need to handle indent levels of 5, 9, etc: these
do not occur (at least in the code we generate);