Fix more windows build warnings.

src/api.cc

Index: src/api.cc
diff --git a/src/api.cc b/src/api.cc
index c8d5a9c19054aa02c5a73e24a10b58101c0f420f..bbed6107880b3e7ecef39d279dc40c937b28edf9 100644
--- a/src/api.cc
+++ b/src/api.cc
@@ -4943,15 +4943,17 @@ Local<String> v8::String::NewExternal(ExternalLatin1StringResource* resource,
   ENTER_V8(isolate);
   ASSERT((encoding & kStringEncodingMask) == LATIN1_ENCODING);
   CHECK(resource && resource->data());
-  bool ascii_hint = (encoding & kAsciiHintMask);
+  int ascii_hint = (encoding & kAsciiHintMask);
   i::Handle<i::String> result;
 
   if (ascii_hint == ASCII_HINT ||
       (ascii_hint != NOT_ASCII_HINT &&
-      i::String::IsAscii(resource->data(), resource->length()))) {
+       i::String::IsAscii(resource->data(),
+                          static_cast<int>(resource->length())))) {
     // Assert that the ascii hint is correct.
     ASSERT(ascii_hint != ASCII_HINT ||
-           i::String::IsAscii(resource->data(), resource->length()));
+           i::String::IsAscii(resource->data(),
+                              static_cast<int>(resource->length())));
     result = NewExternalAsciiStringHandle(isolate, resource);
     isolate->heap()->external_string_table()->AddString(*result);
   } else {
@@ -4959,7 +4961,8 @@ Local<String> v8::String::NewExternal(ExternalLatin1StringResource* resource,
     // since it's not.  Instead, we convert it to an internal string and dispose
     // the external resource.
     result = isolate->factory()->NewStringFromLatin1(
-        i::Vector<const char>(resource->data(), resource->length()),
+        i::Vector<const char>(resource->data(),
+                              static_cast<int>(resource->length())),
         i::NOT_TENURED,
         i::String::NOT_ASCII);
     resource->Dispose();