Bug 1804375 - Re-enable clang -Wnull-dereference warnings in gtest. r=firefox-build-system-reviewers,glandium

Bug 1324242 disabled clang's -Wnull-dereference warnings in gtest code, but this warning can be re-enabled because the current version of gtest doesn't trigger these warnings.

Differential Revision: https://phabricator.services.mozilla.com/D164027

devtools/shared/heapsnapshot/tests/gtest/moz.build

@@ -27,8 +27,6 @@ UNIFIED_SOURCES = [
 # to work around, so we just ignore it.
 if CONFIG["CC_TYPE"] == "clang":
     CXXFLAGS += ["-Wno-inconsistent-missing-override"]
-    # Workaround bug 1142396. Suppress the warning from gmock library for clang.
-    CXXFLAGS += ["-Wno-null-dereference"]
 
 FINAL_LIBRARY = "xul-gtest"
 

layout/base/gtest/moz.build

@@ -23,8 +23,4 @@ LOCAL_INCLUDES += [
     "/layout/style",
 ]
 
-# Workaround bug 1142396. Suppress the warning from gmock library for clang.
-if CONFIG["CC_TYPE"] == "clang":
-    CXXFLAGS += ["-Wno-null-dereference"]
-
 FINAL_LIBRARY = "xul-gtest"

modules/libpref/test/gtest/moz.build

@@ -19,8 +19,6 @@ UNIFIED_SOURCES = [
 # to work around, so we just ignore it.
 if CONFIG["CC_TYPE"] == "clang":
     CXXFLAGS += ["-Wno-inconsistent-missing-override"]
-    # Workaround bug 1142396. Suppress the warning from gmock library for clang.
-    CXXFLAGS += ["-Wno-null-dereference"]
 
 FINAL_LIBRARY = "xul-gtest"