From the talks we had with VM guys, the VM anonymous classes are supposed to be non-verified by default. However, in some cases they are verified, as seen in performance profiles.

Running the targeted test with fastdebug build and -XX:+TraceClassInitialization:
 http://cr.openjdk.java.net/~shade/8059605/unsafe-dac-verify/src/main/java/org/openjdk/UnsafeDefineAnonymousClass.java
 http://cr.openjdk.java.net/~shade/8059605/unsafe-dac-verify/target/test.jar

$ ~/trunks/jdk9-dev/build/linux-x86_64-normal-server-fastdebug/images/j2sdk-image/bin/java -XX:+TraceClassInitialization -jar target/test.jar
...
3325 Initializing 'Class2847'(no method) (0x00000007c033d830)
Start class verification for: Class2848/737945227
End class verification for: Class2848/737945227
3326 Initializing 'Class2848'(no method) (0x00000007c033dc30)
Start class verification for: Class2849/797814020
End class verification for: Class2849/797814020
3327 Initializing 'Class2849'(no method) (0x00000007c033e030)
Start class verification for: Class2850/702846463
End class verification for: Class2850/702846463
...