Bug 1306200 part 1. Move the "report this error now" machinery from Debugger.cpp to ErrorReporting. r=waldo

This allows other consumers to share this machinery.

js/src/vm/Debugger.cpp

@@ -1353,26 +1353,6 @@ Debugger::unwrapPropertyDescriptor(JSContext* cx, HandleObject obj,
     return true;
 }
 
-namespace {
-class MOZ_STACK_CLASS ReportExceptionClosure : public ScriptEnvironmentPreparer::Closure
-{
-public:
-    explicit ReportExceptionClosure(RootedValue& exn)
-        : exn_(exn)
-    {
-    }
-
-    bool operator()(JSContext* cx) override
-    {
-        cx->setPendingException(exn_);
-        return false;
-    }
-
-private:
-    RootedValue& exn_;
-};
-} // anonymous namespace
-
 JSTrapStatus
 Debugger::reportUncaughtException(Maybe<AutoCompartment>& ac)
 {
@@ -1395,13 +1375,11 @@ Debugger::reportUncaughtException(Maybe<AutoCompartment>& ac)
         RootedValue exn(cx);
         if (cx->getPendingException(&exn)) {
             /*
-             * Clear the exception, because
-             * PrepareScriptEnvironmentAndInvoke will assert that we don't
-             * have one.
+             * Clear the exception, because ReportErrorToGlobal will assert that
+             * we don't have one.
              */
             cx->clearPendingException();
-            ReportExceptionClosure reportExn(exn);
-            PrepareScriptEnvironmentAndInvoke(cx, cx->global(), reportExn);
+            ReportErrorToGlobal(cx, cx->global(), exn);
         }
         /*
          * And if not, or if PrepareScriptEnvironmentAndInvoke somehow left

js/src/vm/ErrorReporting.cpp

@@ -12,9 +12,12 @@
 
 #include "jscntxt.h"
 #include "jsexn.h"
+#include "jsfriendapi.h"
 
 using mozilla::Move;
 
+using JS::HandleObject;
+using JS::HandleValue;
 using JS::UniqueTwoByteChars;
 
 void
@@ -118,3 +121,40 @@ js::ReportCompileError(JSContext* cx, ErrorMetadata&& metadata, UniquePtr<JSErro
     if (!cx->helperThread())
         err->throwError(cx);
 }
+
+namespace {
+
+class MOZ_STACK_CLASS ReportExceptionClosure
+  : public js::ScriptEnvironmentPreparer::Closure
+{
+  public:
+    explicit ReportExceptionClosure(HandleValue& exn)
+      : exn_(exn)
+    {
+    }
+
+    bool operator()(JSContext* cx) override
+    {
+        cx->setPendingException(exn_);
+        return false;
+    }
+
+  private:
+    HandleValue& exn_;
+};
+
+} // anonymous namespace
+
+void
+js::ReportErrorToGlobal(JSContext* cx, HandleObject global, HandleValue error)
+{
+    MOZ_ASSERT(!cx->isExceptionPending());
+#ifdef DEBUG
+    // No assertSameCompartment version that doesn't take JSContext...
+    if (error.isObject()) {
+        AssertSameCompartment(global, &error.toObject());
+    }
+#endif // DEBUG
+    ReportExceptionClosure report(error);
+    PrepareScriptEnvironmentAndInvoke(cx, global, report);
+}

js/src/vm/ErrorReporting.h

@@ -86,6 +86,14 @@ extern MOZ_MUST_USE bool
 ReportCompileWarning(JSContext* cx, ErrorMetadata&& metadata, UniquePtr<JSErrorNotes> notes,
                      unsigned flags, unsigned errorNumber, va_list args);
 
+/**
+ * Report the given error Value to the given global.  The JSContext is not
+ * assumed to be in any particular compartment, but the global and error are
+ * expected to be same-compartment.
+ */
+extern void
+ReportErrorToGlobal(JSContext* cx, JS::HandleObject global, JS::HandleValue error);
+
 } // namespace js
 
 #endif /* vm_ErrorReporting_h */