Issue description: The DevTools network profiler is broken for users on stable due to timestamp logic that can cause a race condition, resulting in missing data in the network profiler.

What is the fix: Use previous HTTP profile timestamps instead of DateTime.now() when requesting HTTP profiles. This will eliminate the possibility of a race condition for users with network latency.

Why cherry-pick: Many users are broken with the current behavior. We have received many reports of this breakage and a fix is required to unblock user workflows flutter/devtools#8380.

Risk: Low. The network tool is already broken on stable for many users so this fix will only improve the current state.

Issue link(s): flutter/devtools#8888

Cherry-pick: flutter/devtools#8888
Change-Id: Ib9c643c8116680f6746cc34b7b475c595577bf08
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/409564
Reviewed-by: Elliott Brooks <elliottbrooks@google.com>
Commit-Queue: Kenzie Davisson <kenzieschmoll@google.com>
Reviewed-by: Alexander Thomas <athom@google.com>

Issue description: There was a bug in DDC where generics in factory constructors caused compile time errors. This prevents people from debugging their code on the web when it includes this pattern.

What is the fix: Fix DDC's handling of type environments in factory constructors.

Why cherry-pick: As seen in the Flutter issue linked to below, many people have expressed that this issue is blocking them. People cannot develop on the web if their code includes this pattern.

Risk: The risk here is low, this is an isolated fix to DDC type parameters. It has been tested in internal environments for 2 weeks now and no issues have been discovered.

Issue: flutter/flutter#160338

Cherry-pick: https://dart-review.googlesource.com/c/sdk/+/406344
Change-Id: If32d2343f4ca2d7c9334dfb868fc152a4f431b97
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/410164
Commit-Queue: Nate Biggs <natebiggs@google.com>
Reviewed-by: Slava Egorov <vegorov@google.com>

Issue description: Users are finding that their debug variables are
evaluated to the wrong values and it's due to wildcard variables being
included, but being unable to be evaluated. Wildcard variables shouldn't
be able to be evaluated in the first place.

What is the fix: Correctly propagate the `isWildcard` flag in the CFE to
formal parameters. The VM uses this flag to determine if the variable
can be excluded from debugging evaluation. The flag is now set correctly
with the fix and won't appear in VM debug.

Why cherry-pick: This is causing debug variables to be evaluated
incorrectly because wildcard variables are appearing in the debug panel
of variables and shouldn't be.

Risk: Low, fixes wildcard variables that are formal parameters and touches no other code. This is code that should've been in the feature from the start.

Issue link(s): #60121

Cherry-pick: https://dart-review.googlesource.com/c/sdk/+/410161
Change-Id: Ie7aa3561183e6e326d65c09165a132d6bb3e72a2
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/410640
Reviewed-by: Johnni Winther <johnniwinther@google.com>
Reviewed-by: Siva Annamalai <asiva@google.com>
Commit-Queue: Kevin Chisholm <kevinjchisholm@google.com>

Change-Id: I06a39b1faaf5e4f5e0c0d19ba9be28bb3e4cd5d2
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/412142
Reviewed-by: Alexander Thomas <athom@google.com>
Commit-Queue: Kevin Chisholm <kevinjchisholm@google.com>