Support Firefox stack format

It doesn't include the exception type and message.

libraries/stdlib/js/src/kotlin/throwableExtensions.kt

@@ -68,23 +68,26 @@ private class ExceptionTraceBuilder {
 
     private fun Throwable.dumpSelfTrace(indent: String, qualifier: String): Boolean {
         target.append(indent).append(qualifier)
+        val shortInfo = this.toString()
         if (hasSeen(this)) {
-            target.append("[CIRCULAR REFERENCE, SEE ABOVE: ").append(this).append("]\n")
+            target.append("[CIRCULAR REFERENCE, SEE ABOVE: ").append(shortInfo).append("]\n")
             return false
         }
         visited.asDynamic().push(this)
 
         var stack = this.asDynamic().stack as String?
         if (stack != null) {
+            val stackStart = stack.indexOf(shortInfo).let { if (it < 0) 0 else it + shortInfo.length }
+            if (stackStart == 0) target.append(shortInfo).append("\n")
             if (topStack.isEmpty()) {
                 topStack = stack
-                topStackStart = this.toString().length
+                topStackStart = stackStart
             } else {
-                stack = dropCommonFrames(stack, this.toString().length)
+                stack = dropCommonFrames(stack, stackStart)
             }
             if (indent.isNotEmpty()) {
                 // indent stack, but avoid indenting exception message lines
-                val messageLines = 1 + (message?.count { c -> c == '\n' } ?: 0)
+                val messageLines = if (stackStart == 0) 0 else 1 + shortInfo.count { c -> c == '\n' }
                 stack.lineSequence().forEachIndexed { index: Int, line: String ->
                     if (index >= messageLines) target.append(indent)
                     target.append(line).append("\n")
@@ -93,7 +96,7 @@ private class ExceptionTraceBuilder {
                 target.append(stack).append("\n")
             }
         } else {
-            target.append(this.toString()).append("\n")
+            target.append(shortInfo).append("\n")
         }
 
         val suppressed = suppressedExceptions