Previously, endless method definitions in assignment contexts like
`x = def f = p 1` would fail to parse because command calls (method
calls without parentheses) were only accepted when the surrounding
binding power was less than `PM_BINDING_POWER_COMPOSITION`.

This fix specifically checks for assignment context and allows command
calls in those cases while maintaining the existing behavior for other
contexts. This ensures that:

- `x = def f = p 1` parses correctly (previously failed)
- `private def f = puts "Hello"` still produces the expected error

https://github.com/ruby/prism/commit/722af59ba3

This reverts commit https://github.com/ruby/prism/commit/bc446fb9795e, reversing
changes made to https://github.com/ruby/prism/commit/71432af1eb49.

https://github.com/ruby/prism/commit/e5ca485f4e

Previously, endless method definitions like `x = def f = p 1` would fail
to parse because command calls (method calls without parentheses) were
only accepted when the surrounding binding power was less than
`PM_BINDING_POWER_COMPOSITION` (8). In assignment contexts with binding
power 18, this condition was false, causing parse errors.

This fix ensures command calls are always accepted in endless method
bodies by passing `true` for `accepts_command_call`, making the method
body parse consistently regardless of where the method is defined.

https://github.com/ruby/prism/commit/70413ed4dd