[multiple] Improve video playback in image_picker example (flutter#2819)

This change adds small bugfixes to the following packages:

* video_player_web:
  * Prevent parsing Blob URLs so Safari can play from a PickedFile.
  * Allow users to 'mute' videos by setting their volume to 0.0 (this enables auto-play in most modern browsers)
* video_player:
  * Fix an issue where aspect ratio calculations failed when some of the video sizes were zero (happened in web for incorrect videos)
* image_picker (example app):
  * Start videos in web muted so they can auto-play
  * Dispose video controllers when they're really not needed. This fixes a fatal crash in Safari (not so fatal in other browsers).

[multiple] Improve video playback in image_picker example (flutter#2819)

This change adds small bugfixes to the following packages:

* video_player_web:
  * Prevent parsing Blob URLs so Safari can play from a PickedFile.
  * Allow users to 'mute' videos by setting their volume to 0.0 (this enables auto-play in most modern browsers)
* video_player:
  * Fix an issue where aspect ratio calculations failed when some of the video sizes were zero (happened in web for incorrect videos)
* image_picker (example app):
  * Start videos in web muted so they can auto-play
  * Dispose video controllers when they're really not needed. This fixes a fatal crash in Safari (not so fatal in other browsers).

[multiple] Improve video playback in image_picker example (flutter#2819)

This change adds small bugfixes to the following packages:

* video_player_web:
  * Prevent parsing Blob URLs so Safari can play from a PickedFile.
  * Allow users to 'mute' videos by setting their volume to 0.0 (this enables auto-play in most modern browsers)
* video_player:
  * Fix an issue where aspect ratio calculations failed when some of the video sizes were zero (happened in web for incorrect videos)
* image_picker (example app):
  * Start videos in web muted so they can auto-play
  * Dispose video controllers when they're really not needed. This fixes a fatal crash in Safari (not so fatal in other browsers).

[e2e] Bump version to 0.6.0 (flutter#2855)

Missed this earlier in flutter#2854

[connectivity] Endorse connectivity_for_web. (flutter#2853)

[url_launcher_web] Adds "tel" and "sms" URL support (flutter#2847)

[shared_preferences_linux] Add support for Linux (flutter#2836)

Adds shared_preferences support for Linux.

Part of flutter/flutter#41720

[shared_preferences_linux] Add support for Linux (flutter#2836)

Adds shared_preferences support for Linux.

Part of flutter/flutter#41720

[connectivity_for_web] Introduce connectivity_for_web package. (flutt…

…er#2820)

Move the package formerly known as `experimental_connectivity_web` to flutter/plugins master, as `connectivity_for_web`.

Update README for plugin list (flutter#2843)