Fix signed-unsigned mismatch

Change-Id: Ie7fba8a0fd0475a395205139c4f7169cc94e61b7
Reviewed-on: https://chromium-review.googlesource.com/217510
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Tested-by: Shannon Woods <shannonwoods@chromium.org>
diff --git a/src/libGLESv2/renderer/d3d/d3d9/Renderer9.cpp b/src/libGLESv2/renderer/d3d/d3d9/Renderer9.cpp
index c791342..3047f79 100644
--- a/src/libGLESv2/renderer/d3d/d3d9/Renderer9.cpp
+++ b/src/libGLESv2/renderer/d3d/d3d9/Renderer9.cpp
@@ -1604,7 +1604,7 @@
             }
 
             unsigned short *data = reinterpret_cast<unsigned short*>(mappedMemory);
-            for (int i = 0; i < count; i++)
+            for (size_t i = 0; i < count; i++)
             {
                 data[i] = i;
             }
@@ -1638,7 +1638,7 @@
             }
 
             unsigned int *data = reinterpret_cast<unsigned int*>(mappedMemory);
-            for (int i = 0; i < count; i++)
+            for (size_t i = 0; i < count; i++)
             {
                 data[i] = i;
             }