Various Classfile API-related startup improvements#2

Draft

cl4es wants to merge 13 commits intoasotona:JDK-8294960-invokefrom cl4es:classfile_startup_improvements

+327-229

Commits on Apr 19, 2024

Prefer ClassDesc.ofDescriptor over ClassDesc.of: the former avoids some string processing
cl4es
committed

Commits on Apr 20, 2024

Cache Class.descriptorString in a ClassValue
cl4es
committed

Commits on Apr 21, 2024

Reduce overhead of ObjectMethods::<clinit>
cl4es
committed
charAt(0) instead of startsWith (ClassDesc constructors validate that descriptorString is non-empty)
cl4es
committed

Commits on Apr 23, 2024

Commits on Apr 25, 2024