Add CompileInfo::GetDebugName()

Add CompileInfo::GetDebugName()

Replaces all instances of the code which computed the debug
name of a stub or function with calls to CompileInfo::GetDebugName instead.

Also:
  - Removes useless parameter on CodeStub::GetMajorName
  - Removes FakeStubForTesting since it is no longer required
  - Adds CompileInfo::ShouldEnsureSpaceForLazyDeopt() to replace unclear calls to IsStub().

Review URL: https://codereview.chromium.org/1297203002

Cr-Commit-Position: refs/heads/master@{#30324}