Tint: Add `dual_source_blending` as a valid WGSL extension

This patch adds `dual_source_blending` as a valid WGSL extension
and an alias of `chromium_internal_dual_source_blending` and replaces
`chromium_internal_dual_source_blending` with `dual_source_blending`
in tests when possible.

Bug: chromium:341973423
Change-Id: I724555d2ecab5de7214599e55d97aafd9b6ae559
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/190101
Commit-Queue: Jiawei Shao <jiawei.shao@intel.com>
Reviewed-by: James Price <jrprice@google.com>
diff --git a/src/tint/lang/wgsl/extension_test.cc b/src/tint/lang/wgsl/extension_test.cc
index 9e6c182..0237bd5 100644
--- a/src/tint/lang/wgsl/extension_test.cc
+++ b/src/tint/lang/wgsl/extension_test.cc
@@ -66,6 +66,7 @@
     {"chromium_internal_graphite", Extension::kChromiumInternalGraphite},
     {"chromium_internal_input_attachments", Extension::kChromiumInternalInputAttachments},
     {"chromium_internal_relaxed_uniform_layout", Extension::kChromiumInternalRelaxedUniformLayout},
+    {"dual_source_blending", Extension::kDualSourceBlending},
     {"f16", Extension::kF16},
 };
 
@@ -97,9 +98,12 @@
     {"chromium_internl_relaxyd_uniform_layout", Extension::kUndefined},
     {"chromnnum_internrr77_Gelaxell_uniform_layout", Extension::kUndefined},
     {"chromium_intern4l_relaxe00_uniform_layout", Extension::kUndefined},
-    {"5", Extension::kUndefined},
-    {"u16", Extension::kUndefined},
-    {"f", Extension::kUndefined},
+    {"dua_ource_bledoong", Extension::kUndefined},
+    {"dualsorce_blendzzng", Extension::kUndefined},
+    {"ua_sopiirce_bl11nding", Extension::kUndefined},
+    {"f1XX", Extension::kUndefined},
+    {"55199II", Extension::kUndefined},
+    {"frSSHHa", Extension::kUndefined},
 };
 
 using ExtensionParseTest = testing::TestWithParam<Case>;