compress `apply()` & `call()` of `function` (#2613)

- `fn.apply(a, [ ... ])` => `fn.call(a, ...)`
- `fn.call(a, ... )` => `a, fn(...)`

where `fn` can be `function` literal or symbol reference linked through `reduce_vars`

1 files changed, 28 insertions, 0 deletions

diff --git a/lib/compress.js b/lib/compress.js
index 735b4d2d..af1195d4 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -3857,6 +3857,34 @@ merge(Compressor.prototype, {
                     }
                 }
                 break;
+              case "apply":
+                if (self.args.length == 2 && self.args[1] instanceof AST_Array) {
+                    var args = self.args[1].elements.slice();
+                    args.unshift(self.args[0]);
+                    return make_node(AST_Call, self, {
+                        expression: make_node(AST_Dot, exp, {
+                            expression: exp.expression,
+                            property: "call"
+                        }),
+                        args: args
+                    }).optimize(compressor);
+                }
+                break;
+              case "call":
+                var func = exp.expression;
+                if (func instanceof AST_SymbolRef) {
+                    func = func.fixed_value();
+                }
+                if (func instanceof AST_Function && !func.contains_this()) {
+                    return make_sequence(this, [
+                        self.args[0],
+                        make_node(AST_Call, self, {
+                            expression: exp.expression,
+                            args: self.args.slice(1)
+                        })
+                    ]).optimize(compressor);
+                }
+                break;
             }
         }
         if (compressor.option("unsafe_Func")