Remove redundant information from assert messages.

src/Magnum/PixelFormat.cpp

@@ -35,7 +35,7 @@ namespace Magnum {
 
 UnsignedInt pixelSize(const PixelFormat format) {
     CORRADE_ASSERT(!(UnsignedInt(format) & (1 << 31)),
-        "pixelSize(): can't determine pixel size of an implementation-specific format", {});
+        "pixelSize(): can't determine size of an implementation-specific format", {});
 
     #ifdef __GNUC__
     #pragma GCC diagnostic push
@@ -107,7 +107,7 @@ UnsignedInt pixelSize(const PixelFormat format) {
     #pragma GCC diagnostic pop
     #endif
 
-    CORRADE_ASSERT(false, "pixelSize(): invalid pixel format" << format, {});
+    CORRADE_ASSERT(false, "pixelSize(): invalid format" << format, {});
 }
 
 #ifndef DOXYGEN_GENERATING_OUTPUT

src/Magnum/Test/PixelFormatTest.cpp

@@ -110,8 +110,8 @@ void PixelFormatTest::sizeInvalid() {
     pixelSize(PixelFormat(0xdead));
 
     CORRADE_COMPARE(out.str(),
-        "pixelSize(): invalid pixel format PixelFormat(0x0)\n"
-        "pixelSize(): invalid pixel format PixelFormat(0xdead)\n");
+        "pixelSize(): invalid format PixelFormat(0x0)\n"
+        "pixelSize(): invalid format PixelFormat(0xdead)\n");
 }
 
 void PixelFormatTest::sizeImplementationSpecific() {
@@ -120,7 +120,7 @@ void PixelFormatTest::sizeImplementationSpecific() {
 
     pixelSize(pixelFormatWrap(0xdead));
 
-    CORRADE_COMPARE(out.str(), "pixelSize(): can't determine pixel size of an implementation-specific format\n");
+    CORRADE_COMPARE(out.str(), "pixelSize(): can't determine size of an implementation-specific format\n");
 }
 
 void PixelFormatTest::compressedBlockSize() {