Rethrow exception when swallowing it is not intended.

Source/bindings/v8/V8BindingMacros.h

Index: Source/bindings/v8/V8BindingMacros.h
diff --git a/Source/bindings/v8/V8BindingMacros.h b/Source/bindings/v8/V8BindingMacros.h
index 1dc394acfe3ba66c63af186c05df988d07bff798..5fb8630d5d587eb53773566871185d4214f1e131 100644
--- a/Source/bindings/v8/V8BindingMacros.h
+++ b/Source/bindings/v8/V8BindingMacros.h
@@ -71,28 +71,34 @@ namespace WebCore {
     }
 
 #define TONATIVE_VOID_EXCEPTIONSTATE_INTERNAL(var, value, exceptionState) \
-    var = (value);                                                       \
-    if (UNLIKELY(block.HasCaught()))                                     \
-        exceptionState.rethrowV8Exception(block.Exception());            \
-    if (UNLIKELY(exceptionState.throwIfNeeded()))                        \
+    var = (value);                                                        \
+    if (UNLIKELY(block.HasCaught())) {                                    \
+        exceptionState.rethrowV8Exception(block.Exception());             \

[Jens Widell, 2014/06/16 11:56:39]

Given current usage of this macro and the one below (here, in
V8ElementCustom.cpp and in generated bindings code), I'm pretty sure it's
pointless to call rethrowV8Exception() here now, since 'block' will re-throw the
caught exception on its own, and 'exceptionState' is a local that goes out of
scope when you return.

So I reckon this could be

  if (UNLIKELY(block.HasCaught() || exceptionState.throwIfNeeded()))
    return;

instead.

And if these macros were supposed to be useful in general code, I'd assume the
user would expect the resulting exception to be in 'exceptionState' only, and
not already have been rethrown via the V8 API.

But I'm of course quite new to this code. :-)

[yhirano, 2014/06/17 11:10:02]

Done.

+        return;                                                           \
+    }                                                                     \
+    if (UNLIKELY(exceptionState.throwIfNeeded()))                         \
         return;
 
-#define TONATIVE_VOID_EXCEPTIONSTATE(type, var, value, exceptionState)    \
-    type var;                                                             \
-    {                                                                     \
-        v8::TryCatch block;                                               \
+#define TONATIVE_VOID_EXCEPTIONSTATE(type, var, value, exceptionState)     \
+    type var;                                                              \
+    {                                                                      \
+        v8::TryCatch block;                                                \
+        V8RethrowTryCatchScope rethrow(block);                             \
         TONATIVE_VOID_EXCEPTIONSTATE_INTERNAL(var, value, exceptionState); \
     }
 
 #define TONATIVE_DEFAULT_EXCEPTIONSTATE(type, var, value, exceptionState, retVal) \
-    type var;                                                                 \
-    {                                                                         \
-        v8::TryCatch block;                                                   \
-        var = (value);                                                        \
-        if (UNLIKELY(block.HasCaught()))                                      \
-            exceptionState.rethrowV8Exception(block.Exception());             \
-        if (UNLIKELY(exceptionState.throwIfNeeded()))                         \
-            return retVal;                                                    \
+    type var;                                                                     \
+    {                                                                             \
+        v8::TryCatch block;                                                       \
+        V8RethrowTryCatchScope rethrow(block);                                    \
+        var = (value);                                                            \
+        if (UNLIKELY(block.HasCaught())) {                                        \
+            exceptionState.rethrowV8Exception(block.Exception());                 \
+            return retVal;                                                        \
+        }                                                                         \
+        if (UNLIKELY(exceptionState.throwIfNeeded()))                             \
+            return retVal;                                                        \
     }
 
 // type is an instance of class template V8StringResource<>,