Bugfix: compile negative numbers to unary exprs

Made a typo earlier and there was no unit test to catch it.  There is
now.

Author: anko

src/compile.ls

@@ -4,8 +4,6 @@ looks-like-positive-number = (atom-text) ->
   atom-text.match /^\d+(\.\d+)?$/
 looks-like-negative-number = (atom-text) ->
   atom-text.match /^-\d+(\.\d+)?$/
-looks-like-number = ->
-  (looks-like-positive-number it) || (looks-like-negative-number it)
 
 string-to-estree = ->
   type  : \Literal
@@ -54,7 +52,7 @@ atom-to-estree = (name) ->
   | \true  => lit true
   | \false => lit false
   | otherwise switch
-    | looks-like-number name
+    | looks-like-positive-number name
       type  : \Literal
       value : Number name
       raw   : name

test.ls

@@ -21,10 +21,14 @@ test "first-line shebang" ->
   esl "#!something goes here\n(hello)\n"
     ..`@equals` "hello();"
 
-test "plain literal" ->
+test "plain numeric literal" ->
   esl "3"
     ..`@equals` "3;"
 
+test "plain negative numeric literal" ->
+  esl "-3"
+    ..`@equals` "-3;"
+
 test "plain literal with trailing digits" ->
   esl "asd39"
     ..`@equals` "asd39;"