Remove deprecated RenderArena object and fix stack source path.

tools/deep_memory_profiler/policy.l2.json

 {
   "components": [
     "second",
     "mmap-profiler",
     "mmap-type-profiler",
     "mmap-tcmalloc",
     "FROM_HERE_FOR_TOTAL",
     "mustbezero",
     "unhooked-absent",
     "unhooked-anonymous",
@@ skipping 10 matching lines @@
     "mmap-v8-other",
     "mmap-gpu-mappedmemorymanager",
     "mmap-gpu-command-ringbuffer",
     "mmap-gpu-transfer-ringbuffer",
     "mmap-gpu-gles2-createbuffer",
     "mmap-skia-font",
     "mmap-catch-all",
     "tc-webcore-cachedmatchedproperties",
     "tc-webcore-fontcache",
     "tc-skia",
-    "tc-renderobject",
     "tc-renderstyle",
     "tc-webcore-sharedbuf",
     "tc-webcore-XHRcreate",
     "tc-webcore-XHRreceived",
     "tc-webcore-docwriter-add",
     "tc-webcore-node-and-doc",
     "tc-webcore-node-factory",
     "tc-webcore-element-wrapper",
     "tc-webcore-stylepropertyset",
     "tc-webcore-style-createsheet",
@@ skipping 168 matching lines @@
       "name": "tc-webcore-fontcache",
       "stacktrace": ".*WebCore::FontCache::getFontData.*",
       "allocator": "malloc"
     },
     {
       "name": "tc-skia",
       "stacktrace": ".* Sk[A-Za-z_]+::.*",
       "allocator": "malloc"
     },
     {
-      "name": "tc-renderobject",
-      "stacktrace": ".*WebCore::RenderArena::allocate.*",
-      "allocator": "malloc"
-    },
-    {
       "name": "tc-renderstyle",
       "stacktrace": ".*WebCore::RenderStyle::create.*",
       "allocator": "malloc"
     },
     {
       "name": "tc-renderstyle",
       "stacktrace": ".*WebCore::RenderStyle::clone.*",
       "allocator": "malloc"
     },
     {
@@ skipping 287 matching lines @@
       "allocator": "optional"
     },
     {
       "name": "other",
       "stacktrace": "optional",
       "allocator": "optional"
     }
   ],
   "version": "POLICY_DEEP_3"
 }