deep_memory_profiler: Replace 'WebCore' with 'blink'.

tools/deep_memory_profiler/sorters/malloc.renderer-module.json

 {
   "type": "sorter",
   "version": 1,
   "world": "malloc",
   "name": "renderer-module",
   "order": {},
   "rules": [
     {
       "name": "V8",
       "backtrace_function": ".*v8::.*"
     },
     {
       "name": "Skia",
       "backtrace_function": ".* Sk[A-Z][A-Za-z0-9_]+::.*"
     },
     {
-      "name": "WebCore",
+      "name": "blink",
       "subs": [
-        [ "malloc", "WebCore" ]
+        [ "malloc", "blink" ]
       ],
-      "backtrace_function": ".*WebCore::.*"
+      "backtrace_function": ".*blink::.*"
     },
     {
       "name": "Blink-others",
       "backtrace_function": ".*(WTF::|WebKit::).*"
     },
     {
       "name": "others",
       "backtrace_function": ".*"
     }
   ]
 }