Migrate more SkSL tests to run in dm.

- CastsRoundTowardZero
- Functions
- GeometricIntrinsics
- HelloWorld
- Hex

Other test updates:
- DeadLoopVariable (for-loop structure incompatible with ES2)
- FunctionPrototype (RTE currently disallows calling undef'd functions)
- HexUnsigned (unsigned types incompatible with ES2)

Change-Id: I794bee24dfac55281c9b8b130529888ba2546290
Bug: skia:11009
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/364678
Commit-Queue: John Stiles <johnstiles@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>
diff --git a/gn/sksl_tests.gni b/gn/sksl_tests.gni
index 254e45c..a5a2a59 100644
--- a/gn/sksl_tests.gni
+++ b/gn/sksl_tests.gni
@@ -338,6 +338,7 @@
   "/sksl/shared/Height.sksl",
   "/sksl/shared/HelloWorld.sksl",
   "/sksl/shared/Hex.sksl",
+  "/sksl/shared/HexUnsigned.sksl",
   "/sksl/shared/InstanceID.vert",
   "/sksl/shared/InterfaceBlockNamed.sksl",
   "/sksl/shared/InterfaceBlockNamedArray.sksl",