UserAgent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/54.0.2840.71 Safari/537.36

Example URL:

Steps to reproduce the problem:
1. Set Arial as the default font, and go to any page that contains the archaic letter ꙋ (U+A64B, in Cyrillic Extended-B)
2. It doesn't show up. 
3. Change the default font to Segoe UI (which supports that letter), then the letter shows up.
4. With Segoe UI as default, the codepoint U+A69E in Cyrillic Extended-B doesn't show up, even though I have Quivira (a font supporting that codepoint) properly installed in my system.

This issue also occurs in archaic CJK characters. It seems to me that chrome uses Simsun as the fallback font to display Chinese. But Simsun doesn't cover CJK Ext-E. So whenever I copy/past a character in CJK Ext-E to a webpage, it shows a box. HanaMinB is the only publicly available font that fully supports this code block, and I have it in my system. It doesn't work in chrome.

(I noticed that the CJK Ext-E characters do show up correctly on wikipeda page: https://en.wikipedia.org/wiki/CJK_Unified_Ideographs_Extension_E 
I checked the underlying source code and discovered that it specified 'HanaMinB' in the font list that it wants the browser to use. But if you copy paste it to, say, google, or anywhere else, it becomes a box.)

What is the expected behavior?
If a codepoint is not in the default font or even the fallback font, chrome should scan the system font library and find a font that supports the codepoint. Only when none of the fonts in the font library contains that codepoint should chrome display a box.

But I think a better solution would be the following. Let experienced user determine which  font should be used for a particular unicode range. For example, there is not a single font that covers all CJK, CJK Ext A--E characters. No matter what font you designate as the fallback font for Chinese, it will always fail to display some portion of CJK characters, which total over 80,000 characters. I would like to use SimSun to render CJK, CJK Ext A--D, and HanaMinB for CJK Ext E. 

What went wrong?
(See description above.)

Does it occur on multiple sites: Yes

Is it a problem with a plugin? No 

Did this work before? No 

Does this work in other browsers? N/A

Chrome version: 54.0.2840.71  Channel: stable
OS Version: 10.0
Flash Version: Shockwave Flash 23.0 r0