Type of change

• Refactoring (no functional changes, no api changes)

Description of change

Changes the adapter internal ad markup to remove an explicit call to document.open() on the rendering frame contentDocument in preference to the implicit "open()" steps taken by the user-agent as part of a call to document.write() when a Document is not already open for writing.

Reasoning for the change

Observations in production deployments have shown cases where the write() function of ad markup content Document instance is redefined to equal a function defined on the respective contentWindow; therefore, when the associated contentDocument is open() 'ed, in most user-agents the contentWindow globals and events will be removed.

The result being that the creative markup related to this PR would fail due to a call to an undefined function.

The contentDocument "core" function redefinitions observed were not cases of malicious code; rather, ad quality tooling deployed or implemented by media owners.