RFR: 8210066: [JVMCI] iterateFrames uses wrong GrowableArray API for appending

[Doug Simon]

Please review this small patch to fix an incorrect usage of GrowableArray that can leads to an assertion failure in a fastdebug VM.

Many thanks to Gilles Duboscq for the test showing the problem and confirming that the fix works.

https://bugs.openjdk.java.net/browse/JDK-8210066
http://cr.openjdk.java.net/~dnsimon/8210066/

Testing: hs-tier3-graal

-Doug