fix while and if statements

test/cases/small_conditional/if_end.tst

@@ -1,11 +1,12 @@
 if(0)
-  42
+  four = 42
 end
 -- -- --
-s(:expressions, 
-  s(:if, 
-    s(:condition, 
-      s(:int,  0)), 
-    s(:if_true, 
-      s(:int,  42)), 
-    s(:if_false,  nil)))
+s(:if_statement,
+  s(:condition,
+    s(:int, 0)),
+  s(:true_statements,
+    s(:assignment,
+      s(:name, :four),
+      s(:int, 42))),
+  s(:false_statements, nil))

test/cases/small_conditional/if_end_expressions.tst

@@ -2,17 +2,16 @@ if(3 > var)
   Object.initialize(3)
 end
 -- -- --
-s(:expressions, 
-  s(:if, 
-    s(:condition, 
-      s(:operator,  ">", 
-        s(:int,  3), 
-        s(:name,  :var))), 
-    s(:if_true, 
-      s(:call, 
-        s(:name,  :initialize), 
-        s(:arguments, 
-          s(:int,  3)), 
-        s(:receiver, 
-          s(:module,  "Object")))), 
-    s(:if_false,  nil)))
+s(:if_statement,
+  s(:condition,
+    s(:operator_value, :>,
+      s(:int, 3),
+      s(:name, :var))),
+  s(:true_statements,
+    s(:call,
+      s(:name, :initialize),
+      s(:arguments,
+        s(:int, 3)),
+      s(:receiver,
+        s(:class_name, :Object)))),
+  s(:false_statements, nil))