Security update for webkit2gtk3 (moderate)

This update for webkit2gtk3 to version 2.20.3 fixes the following issues:

These security issues were fixed:

• CVE-2018-4190: An unspecified issue allowed remote attackers to obtain
  sensitive credential information that is transmitted during a CSS
  mask-image fetch (bsc#1097693).
• CVE-2018-4199: An unspecified issue allowed remote attackers to execute
  arbitrary code or cause a denial of service (buffer overflow and
  application crash) via a crafted web site (bsc#1097693)
• CVE-2018-4218: An unspecified issue allowed remote attackers to execute
  arbitrary code or cause a denial of service (memory corruption and
  application crash) via a crafted web site that triggers an
  @generatorState use-after-free (bsc#1097693)
• CVE-2018-4222: An unspecified issue allowed remote attackers to execute
  arbitrary code via a crafted web site that leverages a
  getWasmBufferFromValue
  out-of-bounds read during WebAssembly compilation (bsc#1097693)
• CVE-2018-4232: An unspecified issue allowed remote attackers to
  overwrite cookies via a crafted web site (bsc#1097693)
• CVE-2018-4233: An unspecified issue allowed remote attackers to execute
  arbitrary code or cause a denial of service (memory corruption and
  application crash) via a crafted web site (bsc#1097693)
• CVE-2018-11646: webkitFaviconDatabaseSetIconForPageURL and
  webkitFaviconDatabaseSetIconURLForPageURL mishandle an unset pageURL,
  leading to an application crash (bsc#1095611).

These non-security issues were fixed:

• Disable Gigacage if mmap fails to allocate in Linux.
• Add user agent quirk for paypal website.
• Fix a network process crash when trying to get cookies of about:blank
  page.
• Fix UI process crash when closing the window under Wayland.
• Fix several crashes and rendering issues.

This update was imported from the SUSE:SLE-15:Update update project.