The test page: https://dxr.mozilla.org/mozilla-central/source/layout/reftests/bidi/612843-1.html Layerscope can dump the layer tree, but it can't show the buffer content of that text buffer.
Created attachment 8551105 [details] rtol text on layer viewer I can see the text buffer on layer viewer based on the nightly build today. It looks like the bug is fixed by someone. Perfect!
Created attachment 8551106 [details] backup_rtol.json You can load this json file into the layer viewer tool.
Created attachment 8551107 [details] my testing page, revised from reftests/bidi/612843-1.html Testing page. I load this page on my nightly, and use my Layer viewer to check the layers' buffer.
Looks like current nightly build can dump buffer content for bidi text into Layerscope correctly. If this problem sill happens, just reopen it. Thanks.