Remove caps image storage caps hack.

This was necessary because the number of fragment image storages couldn't be queried in shading language neutral code. We are no longer shading language neutral and this can be queried.

Change-Id: I065a38688919e7cdb1482877a232cb004c8f1511
Reviewed-on: https://skia-review.googlesource.com/5315
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
diff --git a/tests/ImageStorageTest.cpp b/tests/ImageStorageTest.cpp
index 4068174..835aec5 100644
--- a/tests/ImageStorageTest.cpp
+++ b/tests/ImageStorageTest.cpp
@@ -79,7 +79,7 @@
 
     static constexpr int kS = 256;
     GrContext* context = ctxInfo.grContext();
-    if (!context->caps()->shaderCaps()->imageLoadStoreSupport()) {
+    if (context->caps()->shaderCaps()->maxFragmentImageStorages() < 1) {
         return;
     }