[inspector] better isArrayLike for injected-script-source.js

test/inspector/runtime/evaluate-with-generate-preview-expected.txt

 Tests that Runtime.evaluate will generate correct previews.
 
 Running test: testObjectPropertiesPreview
 {
     description : Object
     overflow : false
     properties : [
         [0] : {
             name : p1
             type : object
@@ skipping 809 matching lines @@
     overflow : false
     properties : [
         [0] : {
             name : propNotNamedProto
             type : number
             value : NaN
         }
     ]
     type : object
 }
+
+Running test: testObjWithArrayAsProto
+{
+    description : Array
+    overflow : false
+    properties : [
+    ]
+    type : object

[dgozman, 2017/03/23 21:10:20]

So this was an array before or not? What changed?

[kozy, 2017/03/24 00:40:37]

It was the same before (this test I copied from layout_tests). It's for case
when we have array as prototype: Object.create([1,2]) - in this case we have
splice and length but all values are not own but we assume on frontend side that
values are own. In this case we'll show [undefined, undefined] if pretend this
as real array.

+}