lib: add custom eslint rule against global pollution

This adds a custom eslint rule to make sure the globals are not
polluted in any way by adding extra properties to them in any way.
Besides that it also removes access to `global` by marking some
globals as available to eslint.

lib/.eslintrc.yaml

@@ -31,6 +31,7 @@ rules:
   # Custom rules in tools/eslint-rules
   node-core/lowercase-name-for-primitive: error
   node-core/non-ascii-character: error
+  node-core/no-global-pollute: error
 globals:
   Intl: false
   # Assertions

lib/internal/main/eval_string.js

@@ -12,6 +12,7 @@ const { addBuiltinLibsToObject } = require('internal/modules/cjs/helpers');
 const { getOptionValue } = require('internal/options');
 const source = getOptionValue('--eval');
 prepareMainThreadExecution();
+// eslint-disable-next-line node-core/no-global-pollute
 addBuiltinLibsToObject(global);
 markBootstrapComplete();
 if (getOptionValue('--entry-type') === 'module')

lib/internal/per_context/setup.js

@@ -1,15 +1,14 @@
 // This file is compiled as if it's wrapped in a function with arguments
 // passed by node::NewContext()
-/* global global */
 
 'use strict';
 
 // https://github.com/nodejs/node/issues/14909
-if (global.Intl) {
-  delete global.Intl.v8BreakIterator;
+if (typeof Intl !== 'undefined') {
+  delete Intl.v8BreakIterator;
 }
 
 // https://github.com/nodejs/node/issues/21219
-if (global.Atomics) {
-  delete global.Atomics.wake;
+if (typeof Atomics !== 'undefined') {
+  delete Atomics.wake;
 }

lib/internal/process/execution.js

@@ -62,6 +62,7 @@ function evalScript(name, body, breakFirstLine) {
   const module = new CJSModule(name);
   module.filename = path.join(cwd, name);
   module.paths = CJSModule._nodeModulePaths(cwd);
+  // eslint-disable-next-line node-core/no-global-pollute
   global.kVmBreakFirstLineSymbol = kVmBreakFirstLineSymbol;
   const script = `
     global.__filename = ${JSON.stringify(name)};

tools/eslint-rules/no-global-pollute.js

@@ -0,0 +1,33 @@
+/**
+ * @fileOverview This rule makes sure that the globals don't get polluted by
+ * adding new entries to `global`.
+ * @author Ruben Bridgewater <ruben@bridgewater.de>
+ */
+
+'use strict';
+
+//------------------------------------------------------------------------------
+// Rule Definition
+//------------------------------------------------------------------------------
+
+module.exports = function(context) {
+  const filename = context.getFilename();
+
+  return {
+    'Program:exit': function() {
+      const globalScope = context.getScope();
+      const variable = globalScope.set.get('global');
+      if (variable &&
+          !filename.includes('bootstrap') &&
+          !filename.includes('repl.js')) {
+        const msg = 'Please do not pollute the global scope';
+        variable.references.forEach((reference) => {
+          context.report({
+            node: reference.identifier,
+            message: msg
+          });
+        });
+      }
+    }
+  };
+};