Summary:
When using CSS-Layout in a C# UWP project in x86, by default the MSVC compiler defaults the delegate calling convention to cdecl, while .NET assumes that all delegates are declared using stdcall. This causes a problem when invoking such as this error:
```
Run-Time Check Failure #0 - The value of ESP was not properly saved across
a function call. This is usually a result of calling a function declared with one
calling convention with a function pointer declared with a different calling
convention.
```
This PR changes the calling convention in the C# code to reflect cdecl by using the `UnmanagedFunctionPointer` attribute and setting the calling convention to `CallingConvention.Cdecl`.
```csharp
[UnmanagedFunctionPointer(CallingConvention.Cdecl)]
public delegate CSSSize CSSMeasureFunc(
IntPtr context,
float width,
CSSMeasureMode widthMode,
float height,
CSSMeasureMode heightMode);
```
I have updated all calls as well to other functions. I
Closes https://github.com/facebook/css-layout/pull/231
Reviewed By: emilsjolander
Differential Revision: D4063437
Pulled By: splhack
fbshipit-source-id: b1069a1b9f675d2623a64a1c5f3189292a18a646
1488f822c3