Fix Settings descriptions.

The IR-based minifier was emitting `if (mustDoOpBetweenFloorAndAbs)`
instead of `if (sk_Caps.mustDoOpBetweenFloorAndAbs)`.

Change-Id: Ic258cd306afee6f883c2e6f70b211a1515d53795
Bug: skia:13775
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/585957
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: John Stiles <johnstiles@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>
diff --git a/src/sksl/ir/SkSLSetting.h b/src/sksl/ir/SkSLSetting.h
index 2da1ca8..77c2b9e 100644
--- a/src/sksl/ir/SkSLSetting.h
+++ b/src/sksl/ir/SkSLSetting.h
@@ -54,7 +54,7 @@
     }
 
     std::string description(OperatorPrecedence) const override {
-        return std::string(this->name());
+        return "sk_Caps." + std::string(this->name());
     }
 
 private: