This lets us make it a grammar feature and not a lexer trick.
Newlines are explicitly ignored in some parts of the grammar. This
lets, for example, things like "|" ignore the newline when used as
an operator, but not when used as a parameter delimiter in a block
argument.
Blocks, functions, and methods now have the same code for handling
their bodies.
This means that single-line methods work like single-line functions:
they return the result of their expression.
