Make E2E tests ScopeMirror aware (#149)

* Update package.json

Add `semver` to dependencies for node version checking.

* Update test.js

Add version check in breakpoint fetch and compare
for determination of local or argument array value
lookups. Update `.find` call to use `.matches` property
shorthand.

test/e2e/package.json

@@ -10,6 +10,7 @@
   "license": "Apache-2.0",
   "dependencies": {
     "lodash": "^3.9.3",
-    "q": "^1.4.1"
+    "q": "^1.4.1",
+    "semver": "^5.3.0"
   }
 }

test/e2e/test.js

@@ -28,6 +28,7 @@ var GoogleAuth = require('google-auth-library');
 var _ = require('lodash'); // for _.find. Can't use ES6 yet.
 var Q = require('q');
 var cluster = require('cluster');
+var semver = require('semver');
 
 var DEBUG_API = 'https://clouddebugger.googleapis.com/v2/debugger';
 var SCOPES = [
@@ -209,6 +210,7 @@ function runTest() {
         return promise;
       })
       .then(function(body) {
+        var arg;
         console.log('-- results of get breakpoint\n', body);
         assert.ok(body.breakpoint, 'should have a breakpoint in the response');
         var hit = body.breakpoint;
@@ -219,9 +221,11 @@ function runTest() {
         assert.ok(top.function, 'frame should have a function property');
         assert.strictEqual(top.function, 'fib');
 
-        var arg = _.find(top.arguments, function(a) {
-          return a.name === 'n';
-        });
+        if (semver.satisfies(process.version, '>=4.0')) {
+          arg = _.find(top.locals, {name: 'n'});
+        } else {
+          arg = _.find(top.arguments, {name: 'n'});
+        }
         assert.ok(arg, 'should find the n argument');
         assert.strictEqual(arg.value, '10');
         console.log('-- checking log point was hit again');