Bug 1574972 - Make nsJSUtils::GetCallingLocation() fallible. r=smaug

Some German web sites seem to have started to have file names with
hundreds of thousands of bytes long, which is causing OOM crashes on
Android.

Differential Revision: https://phabricator.services.mozilla.com/D42674

--HG--
extra : moz-landing-system : lando

dom/base/nsJSUtils.cpp

@@ -49,8 +49,7 @@ bool nsJSUtils::GetCallingLocation(JSContext* aContext, nsACString& aFilename,
     return false;
   }
 
-  aFilename.Assign(filename.get());
-  return true;
+  return aFilename.Assign(filename.get(), fallible);
 }
 
 bool nsJSUtils::GetCallingLocation(JSContext* aContext, nsAString& aFilename,
@@ -60,8 +59,7 @@ bool nsJSUtils::GetCallingLocation(JSContext* aContext, nsAString& aFilename,
     return false;
   }
 
-  aFilename.Assign(NS_ConvertUTF8toUTF16(filename.get()));
-  return true;
+  return aFilename.Assign(NS_ConvertUTF8toUTF16(filename.get()), fallible);
 }
 
 uint64_t nsJSUtils::GetCurrentlyRunningCodeInnerWindowID(JSContext* aContext) {