Resolve "RGAA 4: implementation 1.3.x"

Closes #475 (closed)

• 1.3.1 --> see: rgaav4#26
• 1.3.2 --> see: rgaav4#27
• 1.3.3 --> see: rgaav4#28
• 1.3.4 --> see: rgaav4#29
• 1.3.5 --> see: rgaav4#30
• 1.3.6 --> see: rgaav4#31
• 1.3.7 --> see: rgaav4#32
• 1.3.8 --> see: rgaav4#33

Examples:

• https://mdn.mozillademos.org/fr/docs/Tutoriel_canvas/Transformations$samples/A_save_and_restore_canvas_state_example
  • NMI: 1.3.7
  • NMI: 1.3.8
• https://developer.mozilla.org/fr/docs/Web/HTML/Element/header
  • NMI: 1.3.1
• https://webaim.org/techniques/images/
  • NMI: 1.3.1
  • NMI: 1.3.3
• https://codepen.io/cariefisher/pen/bOKEVQ ---> récup multi-testCases.html