Updating names of attachment clear values

Renames multiple attachment clear values to match their new names in the
spec, deprecating the old ones.
 - GPURenderPassColorAttachment.clearColor -> clearValue
 - GPURenderPassDepthStencilAttachment.clearDepth -> depthClearValue
 - GPURenderPassDepthStencilAttachment.clearStencil -> stencilClearValue

Additionally, the old names are marked as deprecated with appropriate
warnings if they are used during the deprecation period.

Bug: dawn:1269
Change-Id: I6649184d65578118942c1f51a41f350719665272
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/80941
Reviewed-by: Shrek Shao <shrekshao@google.com>
Reviewed-by: Austin Eng <enga@chromium.org>
Commit-Queue: Brandon Jones <bajones@chromium.org>
diff --git a/dawn.json b/dawn.json
index eeb5d7c..b3c4025 100644
--- a/dawn.json
+++ b/dawn.json
@@ -1800,7 +1800,8 @@
             {"name": "resolve target", "type": "texture view", "optional": true},
             {"name": "load op", "type": "load op"},
             {"name": "store op", "type": "store op"},
-            {"name": "clear color", "type": "color"}
+            {"name": "clear color", "type": "color", "default": "{ NAN, NAN, NAN, NAN }" },
+            {"name": "clear value", "type": "color" }
         ]
     },
 
@@ -1810,11 +1811,13 @@
             {"name": "view", "type": "texture view"},
             {"name": "depth load op", "type": "load op", "default": "undefined"},
             {"name": "depth store op", "type": "store op", "default": "undefined"},
-            {"name": "clear depth", "type": "float", "default": "0"},
+            {"name": "clear depth", "type": "float", "default": "NAN"},
+            {"name": "depth clear value", "type": "float", "default": "0"},
             {"name": "depth read only", "type": "bool", "default": "false"},
             {"name": "stencil load op", "type": "load op", "default": "undefined"},
             {"name": "stencil store op", "type": "store op", "default": "undefined"},
             {"name": "clear stencil", "type": "uint32_t", "default": "0"},
+            {"name": "stencil clear value", "type": "uint32_t", "default": "0"},
             {"name": "stencil read only", "type": "bool", "default": "false"}
         ]
     },