Fix javac8 compilation failure.

java 8 adds new methods to the javax.lang.model API to deal with jsr308
annotations.

[] build --java_langtools=//third_party/java/jdk/javac8 \
--javabuilder_top=//tools:java/JavaBuilder8_deploy.jar \
//third_party/java_src/compile_testing/javatests:test_lib
...
third_party/java_src/compile_testing/javatests/com/google/testing/compile/EqualityScannerTest.java:58: error: SimpleNewArrayTree is not abstract and does not override abstract method getDimAnnotations() in NewArrayTree
private static class SimpleNewArrayTree implements NewArrayTree {
^
...
https://sponge.[]/6fc84e37-f6b6-4af2-b38e-73edd0addf1e
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Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=62375603