JS: Fix missing variable declarations

The JStg IR update was missing some local variable declarations
that were present earlier, causing global variables to be used
implicitly (or an error in JavaScript strict mode).

This adds the local variable declarations again.

compiler/GHC/StgToJS/Expr.hs

@@ -232,10 +232,10 @@ genEntryLne ctx i rhs@(StgRhsClosure _ext _cc update args body typ) =
               (L.find ((==i) . fst . snd) (zip [0..] vars))
       mk_bh :: G JStgStat
       mk_bh | isUpdatable update =
-              do x <- Var <$> freshIdent
+              do x <- freshIdent
                  return $ mconcat
-                   [ x |= ApplExpr (var "h$bh_lne") [Sub sp (toJExpr myOffset), toJExpr (payloadSize+1)]
-                   , IfStat x (ReturnStat x) mempty
+                   [ x ||= ApplExpr (var "h$bh_lne") [Sub sp (toJExpr myOffset), toJExpr (payloadSize+1)]
+                   , IfStat (Var x) (ReturnStat (Var x)) mempty
                    ]
             | otherwise = pure mempty
   blk_hl <- mk_bh
@@ -913,11 +913,11 @@ loadParams from args = do
                             [ loadIfUsed (from .^ closureField1_) x1 u1
                             , loadIfUsed (from .^ closureField2_) x2 u2
                             ]
-    ((x,u):xs)         -> do d <- Var <$> freshIdent
+    ((x,u):xs)         -> do d <- freshIdent
                              return $ mconcat
                                [ loadIfUsed (from .^ closureField1_) x u
-                               , mconcat [ d |= from .^ closureField2_
-                                         , loadConVarsIfUsed d xs
+                               , mconcat [ d ||= from .^ closureField2_
+                                         , loadConVarsIfUsed (Var d) xs
                                          ]
                                ]
   where