Change order of evaluation for certain indexing operations.

'.foo[.bar]' used to parse like '.foo | .bar as $b | .[$b]',
now it parses like '.bar as $b | .foo | .[$b]'.

testdata

@@ -464,3 +464,7 @@ unique
 [min,max,min_by(.),max_by(.)]
 []
 [null,null,null,null]
+
+.foo[.baz]
+{"foo":{"bar":4},"baz":"bar"}
+4