Add explicit integer casts

WebKit uses the -Wshorten-64-to-32 flag which warns on these cases.

Bug: 3439
Change-Id: I8c1de60da0f173ca2036e2120e79b857f5f2775f
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1740866
Commit-Queue: James Darpinian <jdarpinian@chromium.org>
Reviewed-by: Kenneth Russell <kbr@chromium.org>
diff --git a/src/libANGLE/renderer/vulkan/FramebufferVk.cpp b/src/libANGLE/renderer/vulkan/FramebufferVk.cpp
index dae582c..d51791f 100644
--- a/src/libANGLE/renderer/vulkan/FramebufferVk.cpp
+++ b/src/libANGLE/renderer/vulkan/FramebufferVk.cpp
@@ -1322,7 +1322,7 @@
         ASSERT(colorRenderTarget);
 
         params.colorFormat            = &colorRenderTarget->getImage().getFormat().imageFormat();
-        params.colorAttachmentIndexGL = colorIndexGL;
+        params.colorAttachmentIndexGL = static_cast<uint32_t>(colorIndexGL);
         params.colorMaskFlags         = colorMaskFlags;
         if (mEmulatedAlphaAttachmentMask[colorIndexGL])
         {
@@ -1436,8 +1436,8 @@
         readFormat = &GetDepthStencilImageToBufferFormat(*readFormat, copyAspectFlags);
     }
 
-    size_t level         = renderTarget->getLevelIndex();
-    size_t layer         = renderTarget->getLayerIndex();
+    uint32_t level       = renderTarget->getLevelIndex();
+    uint32_t layer       = renderTarget->getLayerIndex();
     VkOffset3D srcOffset = {area.x, area.y, 0};
 
     VkImageSubresourceLayers srcSubresource = {};