Fix failing JSON tests for Table.

GeoJSON and Visualisation to go.

test/Table_Tests/src/IO/Json_Spec.enso

@@ -13,7 +13,7 @@ spec = Test.group 'JSON conversion' <|
 
     Test.specify 'should convert tables to a format compatible with Table.from_json' <|
         clothes_json = clothes.to_json
-        Table.from_json clothes_json ['Id', 'Name', 'Quantity', 'Rating', 'Price'] . should_equal clothes
+        Table.from_json (Json.parse clothes_json) ['Id', 'Name', 'Quantity', 'Rating', 'Price'] . should_equal clothes
 
     Test.specify 'should write JSON tables to disk' <|
         out = enso_project.data / 'out.json'
@@ -26,7 +26,7 @@ spec = Test.group 'JSON conversion' <|
         r_1 = JS_Object.from_pairs [['foo', 20], ['bar', 'baz'], ['baz', False]]
         r_2 = JS_Object.from_pairs [['bar', 'xyz'], ['baz', True]]
         r_3 = JS_Object.from_pairs [['baz', False], ['foo', 13]]
-        t = Table.from_json [r_1, r_2, r_3].to_json ['foo', 'bar', 'baz']
+        t = Table.from_json [r_1, r_2, r_3] ['foo', 'bar', 'baz']
         t.columns.map .name . should_equal ['foo', 'bar', 'baz']
         t.at 'foo' . to_vector . should_equal [20, Nothing, 13]
         t.at 'bar' . to_vector . should_equal ['baz', 'xyz', Nothing]