Send deprecation messages for prefixed gradients now that it's possible.

third_party/WebKit/Source/core/frame/Deprecation.cpp

Index: third_party/WebKit/Source/core/frame/Deprecation.cpp
diff --git a/third_party/WebKit/Source/core/frame/Deprecation.cpp b/third_party/WebKit/Source/core/frame/Deprecation.cpp
index e8ab30e7254d6fb9d7fa987897f9d47249673923..0fe9983d09db582b87664e516079a25dee5f353a 100644
--- a/third_party/WebKit/Source/core/frame/Deprecation.cpp
+++ b/third_party/WebKit/Source/core/frame/Deprecation.cpp
@@ -442,6 +442,24 @@ String Deprecation::deprecationMessage(UseCounter::Feature feature) {
       return willBeRemoved("indexedDB.webkitGetDatabaseNames()", M60,
                            "5725741740195840");
 
+    case UseCounter::DeprecatedWebKitLinearGradient:
+      return replacedBy("-webkit-linear-gradient", "linear-gradient");
+
+    case UseCounter::DeprecatedWebKitRepeatingLinearGradient:
+      return replacedBy("-webkit-repeating-linear-gradient",
+                        "repeating-linear-gradient");
+
+    case UseCounter::DeprecatedWebKitGradient:
+      return replacedBy("-webkit-gradient",
+                        "linear-gradient or radial-gradient");
+
+    case UseCounter::DeprecatedWebKitRadialGradient:
+      return replacedBy("-webkit-radial-gradient", "radial-gradient");
+
+    case UseCounter::DeprecatedWebKitRepeatingRadialGradient:
+      return replacedBy("-webkit-repeating-radial-gradient",
+                        "repeating-radial-gradient");
+
     // Features that aren't deprecated don't have a deprecation message.
     default:
       return String();