Translate statement and place it in its own block.
fn blockify(t: *Translator, scope: *Scope, stmt: Node.Index) TransError!ZigNode
fn blockify(t: *Translator, scope: *Scope, stmt: Node.Index) TransError!ZigNode {
var block_scope = try Scope.Block.init(t, scope, false);
defer block_scope.deinit();
const result = try t.transStmt(&block_scope.base, stmt);
try block_scope.statements.append(t.gpa, result);
return block_scope.complete();
}