Perform lookups from obj locals with right sb

When object fields are evaluated the locals from the object
are added to the environment. These locals should have the same
environment as the field, in particular they should be
at the same inheritance level. Instead they were evaluated as if
they were on the level from which original field lookup was performed,
resulting in subtle and hard to debug issues.

testdata/obj_local_right_level.golden

@@ -0,0 +1,3 @@
+{
+   "bar": 1
+}

testdata/obj_local_right_level.jsonnet

@@ -0,0 +1,6 @@
+{
+    bar: 0
+} + {
+    local foo = super.bar + 1,
+    bar: foo
+} + {} + {} + {}

testdata/obj_local_right_level2.golden

@@ -0,0 +1,4 @@
+{
+   "answer": "right",
+   "bar": "right"
+}

testdata/obj_local_right_level2.jsonnet

@@ -0,0 +1,7 @@
+{
+    local foo = self.bar,
+    bar: "wrong",
+    answer: foo
+} + {
+    bar: "right"
+}

testdata/obj_local_right_level3.golden

@@ -0,0 +1,4 @@
+{
+   "answer": "right",
+   "bar": "wrong2"
+}

testdata/obj_local_right_level3.jsonnet

@@ -0,0 +1,9 @@
+{
+    bar: "right",
+} + {
+    local foo = super.bar,
+    bar: "wrong1",
+    answer: foo,
+} + {
+    bar: "wrong2"
+}

value.go

@@ -648,7 +648,7 @@ func objectIndex(i *interpreter, trace TraceElement, sb selfBinding, fieldName s
 	}
 
 	fieldSelfBinding := selfBinding{self: sb.self, superDepth: foundAt}
-	fieldUpValues := prepareFieldUpvalues(sb, upValues, locals)
+	fieldUpValues := prepareFieldUpvalues(fieldSelfBinding, upValues, locals)
 
 	return field.field.evaluate(i, trace, fieldSelfBinding, fieldUpValues, fieldName)
 }