Fix ImageData constructor infelicity.

Source/core/html/ImageData.cpp

Index: Source/core/html/ImageData.cpp
diff --git a/Source/core/html/ImageData.cpp b/Source/core/html/ImageData.cpp
index 6b80be777cc5a465afd0fa926f1ed46d98f562d1..8268be7f68b0bc6d6bb3fbf5ba101e0fbbdea759 100644
--- a/Source/core/html/ImageData.cpp
+++ b/Source/core/html/ImageData.cpp
@@ -84,42 +84,63 @@ PassRefPtrWillBeRawPtr<ImageData> ImageData::create(unsigned width, unsigned hei
     return adoptRefWillBeNoop(new ImageData(IntSize(width, height)));
 }
 
-PassRefPtrWillBeRawPtr<ImageData> ImageData::create(DOMUint8ClampedArray* data, unsigned width, unsigned height, ExceptionState& exceptionState)
+bool ImageData::validateConstructorArguments(DOMUint8ClampedArray* data, unsigned width, unsigned& lengthInPixels, ExceptionState& exceptionState)
 {
-    if (!RuntimeEnabledFeatures::imageDataConstructorEnabled()) {
-        exceptionState.throwTypeError("Illegal constructor");
-        return nullptr;
-    }
-    if (!data) {
-        exceptionState.throwTypeError("Expected a Uint8ClampedArray as first argument.");
-        return nullptr;
-    }
     if (!width) {
         exceptionState.throwDOMException(IndexSizeError, "The source width is zero or not a number.");
-        return nullptr;
+        return false;
     }
-
+    ASSERT(data);
     unsigned length = data->length();
     if (!length) {
         exceptionState.throwDOMException(IndexSizeError, "The input data has a zero byte length.");
-        return nullptr;
+        return false;
     }
     if (length % 4) {
         exceptionState.throwDOMException(IndexSizeError, "The input data byte length is not a multiple of 4.");
-        return nullptr;
+        return false;
     }
     length /= 4;
     if (length % width) {
         exceptionState.throwDOMException(IndexSizeError, "The input data byte length is not a multiple of (4 * width).");
+        return false;
+    }
+    lengthInPixels = length;
+    return true;
+}
+
+PassRefPtrWillBeRawPtr<ImageData> ImageData::create(DOMUint8ClampedArray* data, unsigned width, ExceptionState& exceptionState)
+{
+    if (!RuntimeEnabledFeatures::imageDataConstructorEnabled()) {
+        exceptionState.throwTypeError("Illegal constructor");
         return nullptr;
     }
-    if (!height) {
-        height = length / width;
-    } else if (height != length / width) {
-        exceptionState.throwDOMException(IndexSizeError, "The input data byte length is not equal to (4 * width * height).");
+    unsigned lengthInPixels = 0;
+    if (!validateConstructorArguments(data, width, lengthInPixels, exceptionState)) {
+        ASSERT(exceptionState.hadException());
         return nullptr;
     }
+    ASSERT(lengthInPixels && width);
+    unsigned height = lengthInPixels / width;
+    return adoptRefWillBeNoop(new ImageData(IntSize(width, height), data));
+}
 
+PassRefPtrWillBeRawPtr<ImageData> ImageData::create(DOMUint8ClampedArray* data, unsigned width, unsigned height, ExceptionState& exceptionState)
+{
+    if (!RuntimeEnabledFeatures::imageDataConstructorEnabled()) {
+        exceptionState.throwTypeError("Illegal constructor");
+        return nullptr;
+    }
+    unsigned lengthInPixels = 0;
+    if (!validateConstructorArguments(data, width, lengthInPixels, exceptionState)) {
+        ASSERT(exceptionState.hadException());
+        return nullptr;
+    }
+    ASSERT(lengthInPixels && width);
+    if (height != lengthInPixels / width) {
+        exceptionState.throwDOMException(IndexSizeError, "The input data byte length is not equal to (4 * width * height).");
+        return nullptr;
+    }
     return adoptRefWillBeNoop(new ImageData(IntSize(width, height), data));
 }