Add null check in String::fromUTF8()

[Alp Toker]

String::fromUTF8() crashes when passed a null pointer. This behaviour is inconsistent with the other constructors, which return a null String() in this case:

String::String(const char* str)
{
    if (!str)
        return;
    m_impl = StringImpl::create(str);
}

String::String(const char* str, unsigned length)
{
    if (!str)
        return;
    m_impl = StringImpl::create(str, length);
}

Fix attached. This allows us to simplify (or avoid) null checking logic wherever String::fromUTF8() is used.

[Alp Toker]

Created attachment 22692 [details]
Add null checks

[Eric Seidel (no email)]

Comment on attachment 22692 [details]
Add null checks

Looks fine.

[Jan Alonzo]

landed in r35623