Bug 321021: Add option to preserve exceptions thrown from outermost frames,

rather than convert to error reports.  r=mrbkap, sr=brendan.

js/src/jsapi.c

@@ -3647,7 +3647,7 @@ JS_CompileUCScript(JSContext *cx, JSObject *obj,
 #if JS_HAS_EXCEPTIONS
 # define LAST_FRAME_EXCEPTION_CHECK(cx,result)                                \
     JS_BEGIN_MACRO                                                            \
-        if (!(result))                                                        \
+        if (!(result) && !((cx)->options & JSOPTION_DONT_REPORT_UNCAUGHT))    \
             js_ReportUncaughtException(cx);                                   \
     JS_END_MACRO
 #else

js/src/jsapi.h

@@ -503,6 +503,12 @@ JS_StringToVersion(const char *string);
                                                    called with a null script
                                                    parameter, by native code
                                                    that loops intensively */
+#define JSOPTION_DONT_REPORT_UNCAUGHT \
+                                JS_BIT(8)       /* When returning from the
+                                                   outermost API call, prevent
+                                                   uncaught exceptions from
+                                                   being converted to error
+                                                   reports */
 
 extern JS_PUBLIC_API(uint32)
 JS_GetOptions(JSContext *cx);