mdn content work

looking into ...

• Issue with "Intersection Observer API": non-zero intersection rectangle · Issue #10878 · mdn/content
• Issue with animate Firefox is inconsistent in rendering svg - graphic · Issue #8551 · mdn/content
• Issue with "Using shadow DOM": (short summary here please) · Issue #9121 · mdn/content
• Issue with "TextMetrics": (short summary here please) · Issue #11116 · mdn/content
• Issue with "justify-items": states 'right' behaves the same as 'start' this should read 'end' · Issue #11138 · mdn/content

Complete

• Issue with "Inputs and input sources": (short summary here please) · Issue #9311 · mdn/content
• Issue with "Intersection Observer API": ( explanation not complete under "Intersection observer concepts and usage") · Issue #8696 · mdn/content
• Issue with "Building a cross-browser extension": Informtion involving Edge store is incorrect. · Issue #7032 · mdn/content