build: update to latest MDC canary and fix error (#19132)

Updates to the latest Canary version of MDC and fixes a build error.

Author: crisbeto

package.json

@@ -58,7 +58,7 @@
     "@types/youtube": "^0.0.38",
     "@webcomponents/custom-elements": "^1.1.0",
     "core-js": "^2.6.9",
-    "material-components-web": "6.0.0-canary.c4b4bba96.0",
+    "material-components-web": "6.0.0-canary.deda86d8c.0",
     "rxjs": "^6.5.3",
     "systemjs": "0.19.43",
     "tslib": "^1.10.0",

src/material-experimental/mdc-helpers/BUILD.bazel

@@ -73,6 +73,8 @@ sass_library(
         "@npm//:node_modules/@material/dialog/_mixins.scss",
         "@npm//:node_modules/@material/dialog/_variables.import.scss",
         "@npm//:node_modules/@material/dialog/_variables.scss",
+        "@npm//:node_modules/@material/dom/_index.scss",
+        "@npm//:node_modules/@material/dom/_mixins.scss",
         "@npm//:node_modules/@material/drawer/_index.scss",
         "@npm//:node_modules/@material/drawer/_mixins.import.scss",
         "@npm//:node_modules/@material/drawer/_mixins.scss",