Re-land of Use parenthesis in descriptions for array/map/set lengths/sizes

test/inspector/runtime/length-or-size-description.js

Index: test/inspector/runtime/length-or-size-description.js
diff --git a/test/inspector/runtime/length-or-size-description.js b/test/inspector/runtime/length-or-size-description.js
new file mode 100644
index 0000000000000000000000000000000000000000..4e91f7f54bb4431cc29ad340bd898c3cd48c0b87
--- /dev/null
+++ b/test/inspector/runtime/length-or-size-description.js
@@ -0,0 +1,23 @@
+// Copyright 2016 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+print("Test that descriptions for arrays, maps, and sets include the correct length or size.")
+
+Promise.all([
+  testExpression("new Set()"),
+  testExpression("new Set([1,2])"),
+  testExpression("new Map()"),
+  testExpression("new Map([[1,2],[3,4]])"),
+  testExpression("new Array()"),
+  testExpression("new Array(2)"),
+  testExpression("new Uint8Array()"),
+  testExpression("new Uint8Array(2)")
+]).then(() => InspectorTest.completeTest());
+
+function testExpression(expression) {
+  return Protocol.Runtime.evaluate({ expression: expression })
+            .then(result => InspectorTest.logMessage(result.result.result.description))
+            .then(() => Protocol.Runtime.evaluate({ expression: "[" + expression + "]", generatePreview: true }))
+            .then(result => InspectorTest.logMessage(result.result.result.preview.properties[0].value))
+}