deduplicate AST_Super & AST_This logic (#2366)

lib/ast.js

@@ -1042,7 +1042,7 @@ var AST_This = DEFNODE("This", null, {
 
 var AST_Super = DEFNODE("Super", null, {
     $documentation: "The `super` symbol",
-}, AST_Symbol);
+}, AST_This);
 
 var AST_Constant = DEFNODE("Constant", null, {
     $documentation: "Base class for all constants",

lib/compress.js

@@ -610,7 +610,6 @@ merge(Compressor.prototype, {
     }
 
     function is_lhs_read_only(lhs) {
-        if (lhs instanceof AST_Super) return true;
         if (lhs instanceof AST_This) return true;
         if (lhs instanceof AST_SymbolRef) return lhs.definition().orig[0] instanceof AST_SymbolLambda;
         if (lhs instanceof AST_PropAccess) {
@@ -2143,7 +2142,6 @@ merge(Compressor.prototype, {
 
         def(AST_EmptyStatement, return_false);
         def(AST_Constant, return_false);
-        def(AST_Super, return_false);
         def(AST_This, return_false);
 
         def(AST_Call, function(compressor){
@@ -2838,7 +2836,6 @@ merge(Compressor.prototype, {
 
         def(AST_Node, return_this);
         def(AST_Constant, return_null);
-        def(AST_Super, return_null);
         def(AST_This, return_null);
         def(AST_Call, function(compressor, first_in_statement){
             if (!this.is_expr_pure(compressor)) {
@@ -4832,7 +4829,7 @@ merge(Compressor.prototype, {
             var has_special_symbol = false;
             self.walk(new TreeWalker(function(node) {
                 if (has_special_symbol) return true;
-                if (node instanceof AST_Super || node instanceof AST_This) {
+                if (node instanceof AST_This) {
                     has_special_symbol = true;
                     return true;
                 }

lib/output.js

@@ -1685,9 +1685,6 @@ function OutputStream(options) {
     DEFPRINT(AST_Symbol, function (self, output) {
         self._do_print(output);
     });
-    DEFPRINT(AST_SymbolDeclaration, function(self, output){
-        self._do_print(output);
-    });
     DEFPRINT(AST_Hole, noop);
     DEFPRINT(AST_This, function(self, output){
         output.print("this");

test/compress/arrow.js

@@ -631,3 +631,31 @@ issue_2271: {
     }
     expect_stdout: "PASS"
 }
+
+concise_method_with_super: {
+    options = {
+        arrows: true,
+    }
+    input: {
+        var o = {
+            f: "FAIL",
+            g() {
+                return super.f;
+            }
+        }
+        Object.setPrototypeOf(o, { f: "PASS" });
+        console.log(o.g());
+    }
+    expect: {
+        var o = {
+            f: "FAIL",
+            g() {
+                return super.f;
+            }
+        }
+        Object.setPrototypeOf(o, { f: "PASS" });
+        console.log(o.g());
+    }
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}