Parser swallows leading whitespace after indented placeable

In this fixture, the leading whitespace in front of "four" is preserved as expected:
```
key12 =
{ "." }
    four
```
However, with normalized indentation, it is not:
```
key12 =
    { "." }
        four
```
This is wrongly parsed to the same AST as this:
```
key12 =
    { "." }
    four
```