Fix issues with JS backend syntax translation

- Fixed some issues with the JS backend syntax translation introduced by
  ghcjs#135.

GHCJS/Buffer.hs

@@ -192,7 +192,7 @@ foreign import javascript unsafe
 foreign import javascript unsafe
   "h$wrapBuffer" js_wrapBuffer :: SomeArrayBuffer any -> SomeBuffer any
 foreign import javascript unsafe
-  "h$wrapBuffer($1.buf.slice($1.u8.byteOffset, $1.len))"
+  "((x) => { return h$wrapBuffer(x.buf.slice(x.u8.byteOffset, x.len)); })"
   js_clone :: SomeBuffer any1 -> IO (SomeBuffer any2)
 foreign import javascript unsafe
   "((x) => { return x.len; })" js_byteLength :: SomeBuffer any -> Int

JavaScript/Web/Canvas.hs

@@ -345,9 +345,9 @@ foreign import javascript unsafe "(($1,$2,$3,$4,$5,$6,$7) => { $7.transform($1,$
   js_transform :: Double -> Double -> Double -> Double -> Double -> Double -> Context -> IO ()
 foreign import javascript unsafe "(($1,$2,$3,$4,$5,$6,$7) => { $7.setTransform($1,$2,$3,$4,$5,$6); })"
   js_setTransform :: Double -> Double -> Double -> Double -> Double -> Double -> Context -> IO ()
-foreign import javascript unsafe "((x,y,z) => { x.scale(x,y); })"
+foreign import javascript unsafe "((x,y,z) => { z.scale(x,y); })"
   js_scale :: Double -> Double -> Context -> IO ()
-foreign import javascript unsafe "((x,y,z) => { x.translate(x,y); })"
+foreign import javascript unsafe "((x,y,z) => { z.translate(x,y); })"
   js_translate  :: Double -> Double -> Context -> IO ()
 foreign import javascript unsafe "((x,y) => { y.rotate(x); })"
   js_rotate :: Double -> Context -> IO ()
@@ -363,9 +363,9 @@ foreign import javascript unsafe "((x) => { x.closePath(); })"
   js_closePath :: Context -> IO ()
 foreign import javascript unsafe "((x) => { x.clip(); })"
   js_clip  :: Context -> IO ()
-foreign import javascript unsafe "((x,y,z) => { x.moveTo(x,y); })"
+foreign import javascript unsafe "((x,y,z) => { z.moveTo(x,y); })"
   js_moveTo :: Double -> Double -> Context -> IO ()
-foreign import javascript unsafe "((x,y,z) => { x.lineTo(x,y); })"
+foreign import javascript unsafe "((x,y,z) => { z.lineTo(x,y); })"
   js_lineTo :: Double -> Double -> Context -> IO ()
 foreign import javascript unsafe "(($1,$2,$3,$4,$5) => { $5.quadraticCurveTo($1,$2,$3,$4); })"
   js_quadraticCurveTo :: Double -> Double -> Double -> Double -> Context -> IO ()
@@ -377,7 +377,7 @@ foreign import javascript unsafe "(($1,$2,$3,$4,$5,$6) => { $6.arcTo($1,$2,$3,$4
   js_arcTo :: Double -> Double -> Double -> Double -> Double -> Context -> IO ()
 foreign import javascript unsafe "(($1,$2,$3,$4,$5) => { $5.rect($1,$2,$3,$4); })"
   js_rect :: Double -> Double -> Double -> Double -> Context -> IO ()
-foreign import javascript unsafe "((x,y,z) => { x.isPointInPath(x,y); })"
+foreign import javascript unsafe "((x,y,z) => { z.isPointInPath(x,y); })"
   js_isPointInPath :: Double -> Double -> Context -> IO ()
 foreign import javascript unsafe
   "(($1,$2,$3,$4,$5) => { $5.fillStyle = 'rgba(' + $1 + ',' + $2 + ',' + $3 + ',' + $4 + ')'; })"
@@ -420,13 +420,13 @@ foreign import javascript unsafe "(($1,$2,$3,$4,$5) => { $5.strokeRect($1,$2,$3,
   js_strokeRect :: Double -> Double -> Double -> Double -> Context -> IO ()
 foreign import javascript unsafe "(($1,$2,$3,$4,$5,$6) => { $6.drawImage($1,$2,$3,$4,$5); })"
   js_drawImage :: Image -> Int -> Int -> Int -> Int -> Context -> IO () 
-foreign import javascript unsafe "((x,y,z) => { return x.createPattern(x,y); })"
+foreign import javascript unsafe "((x,y,z) => { return z.createPattern(x,y); })"
   js_createPattern :: Image -> JSString -> Context -> IO Pattern
 foreign import javascript unsafe "((x) => { return x.width; })"
   js_width :: Canvas -> IO Int
 foreign import javascript unsafe "((x) => { return x.height; })"
   js_height :: Canvas -> IO Int
-foreign import javascript unsafe "((x,y) => { return y.width = x;; })"
+foreign import javascript unsafe "((x,y) => { return y.width = x; })"
   js_setWidth :: Int -> Canvas -> IO ()
-foreign import javascript unsafe "((x,y) => { return y.height = x;; })"
+foreign import javascript unsafe "((x,y) => { return y.height = x; })"
   js_setHeight :: Int -> Canvas -> IO ()

JavaScript/Web/XMLHttpRequest.hs

@@ -215,13 +215,13 @@ foreign import javascript unsafe
   "((x) => { return x.abort(); })"
   js_abort :: XHR -> IO ()
 foreign import javascript unsafe
-  "((x,y,z) => { x.setRequestHeader(x,y); })"
+  "((x,y,z) => { z.setRequestHeader(x,y); })"
   js_setRequestHeader :: JSString -> JSString -> XHR -> IO ()
 foreign import javascript unsafe
-  "((x,y,z) => { x.open(x,y); })"
+  "((x,y,z) => { z.open(x,y); })"
   js_open2 :: JSString -> JSString -> XHR -> IO ()
 foreign import javascript unsafe
-  "(($1,$2,$3,$4,$5) => { $5.open($1,$2,true,$4,$5); })"
+  "(($1,$2,$3,$4,$5) => { $5.open($1,$2,true,$3,$4); })"
   js_open4 :: JSString -> JSString -> JSString -> JSString -> XHR -> IO ()
 foreign import javascript unsafe
   "new FormData()"