Don't require => in named tuples to be infix

This isn't required in old lowering, and is difficult to preserve in the
presence of `Expr` macros. It's also an awkward/wrong use of flags given
that we've already arranged the associated `K"call"` node by the time we
get to desugaring.

Author: c42f

src/desugaring.jl

@@ -1568,7 +1568,7 @@ function expand_named_tuple(ctx, ex, kws;
             end
             name = to_symbol(ctx, kw[2])
             value = kw
-        elseif k == K"call" && is_infix_op_call(kw) && numchildren(kw) == 3 &&
+        elseif k == K"call" && numchildren(kw) == 3 &&
                 is_same_identifier_like(kw[1], "=>")
             # a=>b   ==>  $a=b
             appended_nt = _named_tuple_expr(ctx, kw, (kw[2],), (kw[3],))

src/macro_expansion.jl

@@ -301,10 +301,7 @@ function expand_forms_1(ctx::MacroExpansionContext, ex::SyntaxTree)
                 k = K"dotcall"
                 farg = farg[1]
             end
-            # Preserve call type flags (mostly ignored in the next pass as
-            # we've already reordered arguments.)
-            callflags = JuliaSyntax.call_type_flags(ex)
-            @ast ctx ex [k(syntax_flags=(callflags == 0 ? nothing : callflags))
+            @ast ctx ex [k
                 expand_forms_1(ctx, farg)
                 (expand_forms_1(ctx, a) for a in args)...
             ]