make core_graphics public for other project such as metal-rs to pass…

[Michael-Lfx]

make core_graphics public for other project such as metal-rs to pass iOS compilation

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This change is 

[jrmuizel]

Why is this needed for iOS compilation?

[Michael-Lfx]

Because metal-rs use NSSize as return value. Compilation for macOS is good. For iOS, there is no NSSize definition in Foundation, instead we could use CGSize which defined in Core Graphics Framework. Here is metal-rs code snippet.

pub fn drawable_size(&self) -> NSSize {
    unsafe {
        msg_send![self, drawableSize]
    }
}

pub fn set_drawable_size(&self, size: NSSize) {
    unsafe {
        msg_send![self, setDrawableSize:size]
    }
}

[jrmuizel]

Shouldn't metal-rs be using the type from the core graphics crate directly?

[bors-servo]

☔ The latest upstream changes (presumably #259) made this pull request unmergeable. Please resolve the merge conflicts.

[jrmuizel]

Closing for inactivity from author.