bindings: Add toBoolean() to V8Binding.h

Source/bindings/core/v8/V8Binding.h

Index: Source/bindings/core/v8/V8Binding.h
diff --git a/Source/bindings/core/v8/V8Binding.h b/Source/bindings/core/v8/V8Binding.h
index 9b6b2fdf371356204a539ee315c72835bd7dab68..13bc55f0272bdc22be4b60bb37088cc4eeaa4532 100644
--- a/Source/bindings/core/v8/V8Binding.h
+++ b/Source/bindings/core/v8/V8Binding.h
@@ -387,6 +387,18 @@ enum IntegerConversionConfiguration {
     Clamp
 };
 
+// Convert a value to a boolean.
+inline bool toBoolean(v8::Isolate* isolate, v8::Local<v8::Value> value, ExceptionState& exceptionState)
+{
+    if (value->IsBoolean())

[vivekg, 2015/04/10 05:43:47]

Shall we split this into fast (inline toBoolean) and slower (non-inline
toBooleanSlow) path as is the case with other conversions?

[vivekg, 2015/04/10 05:47:36]

Or may be wrap it using 

inline bool toBoolean(v8::Isolate* isolate, v8::Local<v8::Value> value,
ExceptionState& exceptionState)
{
    if (LIKELY(value->IsBoolean()))
        return value.As<v8::Boolean>()->Value();

    ...
}

[haraken, 2015/04/10 05:48:01]

Yeah, it's good to minimize the inlined part. We can move the TryCatch part into
.cpp.

[bashi, 2015/04/10 06:39:54]

Done.

+        return value.As<v8::Boolean>()->Value();
+    v8::TryCatch block;
+    bool result = false;
+    if (!v8Call(value->BooleanValue(isolate->GetCurrentContext()), result, block))
+        exceptionState.rethrowV8Exception(block.Exception());
+    return result;
+}
+
 // Convert a value to a 8-bit signed integer. The conversion fails if the
 // value cannot be converted to a number or the range violated per WebIDL:
 // http://www.w3.org/TR/WebIDL/#es-byte