[tint][ir][fuzz] Disable default corpus generation

Due to the corpus taking a long time to generate, and possibly being
misformatted, removing it as a dependency of tint_ir_fuzzer. It can
still be generated via invoking the action directly.

Issues: 343218481, 345377541
Change-Id: I24e73f19c68f792dc68e4cbc0e446fe2dc4e842e
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/192221
Commit-Queue: Ryan Harrison <rharrison@chromium.org>
Auto-Submit: Ryan Harrison <rharrison@chromium.org>
Reviewed-by: James Price <jrprice@google.com>
Commit-Queue: James Price <jrprice@google.com>
diff --git a/src/tint/tint.gni b/src/tint/tint.gni
index 956f96c..cefcc42 100644
--- a/src/tint/tint.gni
+++ b/src/tint/tint.gni
@@ -195,10 +195,18 @@
         seed_corpus = fuzzer_corpus_wgsl_dir
         seed_corpus_deps = [ "${tint_src_dir}:tint_generate_wgsl_corpus" ]
       } else if (target_name == "ir") {
-        if (tint_build_cmds) {
-          seed_corpus = fuzzer_corpus_ir_dir
-          seed_corpus_deps = [ "${tint_src_dir}:tint_generate_ir_corpus" ]
-        }
+        # The IR corpus takes a long time to generate and may not
+        # actually be correctly formatted (crbug.com/345377541 &
+        # crbug.com/343218481).
+        # Disabling generating it by default until these issues
+        # are resolved.
+        # The corpus can still be generated by explicitly
+        # invoking tint_generate_ir_corpus
+        #
+        # if (tint_build_cmds) {
+        #   seed_corpus = fuzzer_corpus_ir_dir
+        #   seed_corpus_deps = [ "${tint_src_dir}:tint_generate_ir_corpus" ]
+        # }
       } else {
         assert(false, "unsupported tint fuzzer target")
       }