Fixes Issue #603 -- a longstanding precedence issue involving prefix vs postfix if and unless, involving using the entire single-line if statment as an expression.

test/test_if.coffee

@@ -64,10 +64,20 @@ ok result is undefined
 
 # Return an if with no else.
 func = ->
-  return (if false then callback())
+  return if false then callback()
 
 ok func() is null
 
+func = ->
+  return unless false then 100 else -100
+
+ok func() is 100
+
+ident = (x) -> x
+result = ident if false then 300 else 100
+
+ok result is 100
+
 
 # If-to-ternary with instanceof requires parentheses (no comment).
 if {} instanceof Object