fix bugs with getter/setter (#1926)

- `reduce_vars`
- `side_effects`
- property access for object
- `AST_SymbolAccessor` as key names

enhance `test/ufuzz.js`
- add object getter & setter
  - property assignment to setter
  - avoid infinite recursion in setter
- fix & adjust assignment operators
  - 50% `=`
  - 25% `+=`
  - 2.5% each for the rest
- avoid "Invalid array length"
- fix `console.log()`
  - bypass getter
  - curb recursive reference
- deprecate `-E`, always report runtime errors

test/compress/reduce_vars.js

@@ -2169,3 +2169,32 @@ issue_1922_2: {
     }
     expect_stdout: "1"
 }
+
+accessor: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+        toplevel: true,
+    }
+    input: {
+        var a = 1;
+        console.log({
+            get a() {
+                a = 2;
+                return a;
+            },
+            b: 1
+        }.b, a);
+    }
+    expect: {
+        var a = 1;
+        console.log({
+            get a() {
+                a = 2;
+                return a;
+            },
+            b: 1
+        }.b, a);
+    }
+    expect_stdout: "1 1"
+}