Test for duplicate symbols/macros (#1955)

* Test for duplicate symbols/macros

We've had a few cases where we accidentally include the same symbol or macro
definition in both macros.js and symbols.js.  This new test automatically
detects these scenarios during Jest testing.

* Fix lint errors

test/dup-spec.js

@@ -0,0 +1,22 @@
+/* global expect: false */
+/* global it: false */
+/* global describe: false */
+
+import symbols from '../src/symbols.js';
+import macros from '../src/macros.js';
+
+describe("Symbols and macros", () => {
+    for (const macro in macros) {
+        if (!macros.hasOwnProperty(macro)) {
+            continue;
+        }
+        it(`macro ${macro} should not shadow a symbol`, () => {
+            for (const kind in symbols) {
+                if (!symbols.hasOwnProperty(kind)) {
+                    continue;
+                }
+                expect(symbols[kind][macro]).toBeFalsy();
+            }
+        });
+    }
+});