[inspector] generate preview for nodes

Some protocol clients would like to have preview for all objects.
Preview for node was removed as part of work on inline values in sources,
we can ignore them on frontend side.

R=pfeldman@chromium.org

Bug: none
Cq-Include-Trybots: master.tryserver.blink:linux_trusty_blink_rel
Change-Id: Ic549ceb654a0e23e4929a2ae2048eed898822b7d
Reviewed-on: https://chromium-review.googlesource.com/1003144Reviewed-by: Pavel Feldman <pfeldman@chromium.org>
Commit-Queue: Aleksey Kozyatinskiy <kozyatinskiy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#52497}

src/inspector/injected-script-source.js

@@ -784,7 +784,7 @@ InjectedScript.RemoteObject = function(object, objectGroupName, doNotBind, force
     if (generatePreview && this.type === "object") {
         if (this.subtype === "proxy")
             this.preview = this._generatePreview(InjectedScriptHost.proxyTargetValue(object), undefined, columnNames, isTable, skipEntriesPreview);
-        else if (this.subtype !== "node")
+        else
             this.preview = this._generatePreview(object, undefined, columnNames, isTable, skipEntriesPreview);
     }