This is a testharness.js-based test.
[FAIL] pasting in contenteditable="plaintext-only" in contenteditable="true": beforeinput
  assert_equals: beforeinput.data should be null expected (object) null but got (string) "abc"
[FAIL] pasting in contenteditable="plaintext-only" in contenteditable="true": innerHTML
  assert_equals: expected "<div contenteditable=\\"true\\"><div contenteditable=\\"plaintext-only\\"><b>abc</b></div></div>" but got "<div contenteditable=\\"true\\"><div contenteditable=\\"plaintext-only\\">abc</div></div>"
[FAIL] pasting in contenteditable="plaintext-only" in contenteditable="true" and contenteditable="false": beforeinput
  assert_equals: beforeinput.data should be null expected (object) null but got (string) "abc"
[FAIL] pasting in contenteditable="true" in contenteditable="plaintext-only": beforeinput
  assert_true: beforeinput.dataTransfer should have the styled text as text/html expected true got false
[FAIL] pasting in contenteditable="true" in contenteditable="plaintext-only" and contenteditable="false": beforeinput
  assert_true: beforeinput.dataTransfer should have the styled text as text/html expected true got false
[FAIL] pasting in contenteditable="true" in contenteditable="plaintext-only" and contenteditable="false": innerHTML
  assert_equals: expected "<div contenteditable=\\"plaintext-only\\"><div contenteditable=\\"false\\"><div contenteditable=\\"true\\"><b>abc</b></div></div></div>" but got "<div contenteditable=\\"plaintext-only\\"><div contenteditable=\\"false\\"><div contenteditable=\\"true\\"><b style=\\"white-space: normal;\\">abc</b></div></div></div>"
Harness: the test ran to completion.