Fixed Bug 40464 Placeholder attribute of searchInput element

Removed the javascript code that sets the placeholder of #searchInput element.
Now the placeholder attribute of #searchInput element is set only in the original HTML.
On browsers that do not support placeholder attribute, placeholder.js will insert
the appropriate placeholder.

Bug: 40464
Change-Id: I6496716f2bd25307004ba16bceadca4c6723a5db
Merge "Fixed Bug 40464 Placeholder attribute of searchInput element"