Ignored Cairo Symbols With Explanations 

Cairo -
cairo_debug_reset_static_data (not needed)

CairoContext - 
cairo_reference (not needed - referencing all handled by PHP)
cairo_destroy (use unset - unreferencing handled by PHP)
cairo_get_reference_count (not needed - referencing all handled by PHP)
cairo_set_user_data (not needed - adding info handled by PHP)
cairo_get_user_data (not needed - adding info handled by PHP)
cairo_rectangle_list_destroy (list is changed to multi-dim-array and implicitly freed)

CairoPath -
cairo_path_destroy (not needed - referencing and destruction all handled by PHP)

CairoPattern -
cairo_pattern_reference (not needed - referencing all handled by PHP)
cairo_pattern_destroy (use unset - unreferencing handled by PHP)
cairo_pattern_get_reference_count (not needed - referencing all handled by PHP)
cairo_pattern_set_user_data (not needed - adding info handled by PHP)
cairo_pattern_get_user_data (not needed - adding info handled by PHP)

CairoSurface - 
cairo_surface_reference (not needed - referencing all handled by PHP)
cairo_surface_destroy (use unset - unreferencing handled by PHP)
cairo_surface_get_reference_count (not needed - referencing all handled by PHP)
cairo_surface_set_user_data (not needed - adding info handled by PHP)
cairo_surface_get_user_data (not needed - adding info handled by PHP)
cairo_surface_write_to_png_stream (wrapped into cairo_surface_write_to_png, use php streams)

CairoImageSurface -
cairo_image_surface_create_from_png_stream (wrapped into cairo_image_surface_create_from_png, use php streams)

CairoSvgSurface -
cairo_svg_surface_create_for_stream (wrapped into cairo_svg_surface_create, use php streams)

CairoPdfSurface -
cairo_pdf_surface_create_for_stream (wrapped into cairo_pdf_surface_create, use php streams)

CairoFontFace -
cairo_font_face_reference (not needed - referencing all handled by PHP)
cairo_font_face_destroy (use unset - unreferencing handled by PHP)
cairo_font_face_get_reference_count (not needed - referencing all handled by PHP)
cairo_font_face_get_user_data  (not needed - adding info handled by PHP)
cairo_font_face_set_user_data  (not needed - adding info handled by PHP)