[dart2js] Defer deserialized CodegenResults by members.
[dart2js] Defer deserialized CodegenResults by members.

For large applications only ~60% of these objects are used. This defers their deserializtion until they're accessed in the codegen member map.

In local testing on large applications this saved ~200MB of memory usage in the linker phase.

Change-Id: I8ff87803fc23ef2d3f954646687e3fc67b68a4f7
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/254600
Commit-Queue: Nate Biggs <4bdbe5a28604b503f0b7346ee4d58c334975887b@google.com>
Reviewed-by: Joshua Litt <9f8daed1ab51574c9a48ffacb03e4a1adb4f880c@google.com>

dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk