UserAgent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/67.0.3396.99 Safari/537.36

Steps to reproduce the problem:
1. Open the sample attached file chromeTest.html (relies on the other 2 attached files being in same folder)
2. Force garbage collection. Perf monitor gives Documents: 4
3. Take heap snapshot.
4. Click the button labelled "Click to reload iframe" on the sample HTML page.
5. Force garbage collection. Perf monitor gives Documents: 5
6. Take heap snapshot.
7. Even though perf monitor says number of documents went up by 1 (from 4 to 5) the number of 'Document' objects on the heap stays the same (as does the number of 'HTMLDocument' objects. You can compare the 2 heap snapshots and the 'delta' column in the summary is zero for both these types of object. So it looks like perf monitor isn't keeping count of the number of documents correctly.

What is the expected behavior?
The performance monitor number of documents should be consistent with the number of 'Document' objects in the heap (or at least shouldn't increase if the number on the heap doesn't increase).

What went wrong?
The performance monitor shows an increasing documents count even though the number of documents on the heap stays the same.

Did this work before? N/A 

Chrome version: 70.0.3501.0 (Official Build) canary (64-bit)  Channel: canary
OS Version: 10.0
Flash Version: 

Please ask if you need more info or diagnostics.
 

Deleted: chromeTest.html 716 bytes

chromeTest.html 716 bytes View Download

Deleted: testContent1.html 41 bytes

testContent1.html 41 bytes View Download

Deleted: testContent2.html 41 bytes

testContent2.html 41 bytes View Download