[Reland] Fix ReadPixels from float fbo buffer in ES2/WebGL1.

third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.cpp

Index: third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.cpp
diff --git a/third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.cpp b/third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.cpp
index 828b87526c2c11865bb0ea7505af94a6f06e7b7a..294e0c46f234963ceb291f12a10d635e4897d627 100644
--- a/third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.cpp
+++ b/third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.cpp
@@ -3548,7 +3548,7 @@ bool WebGLRenderingContextBase::validateReadPixelsFormatAndType(GLenum format, G
         }
         return true;
     case GL_FLOAT:
-        if (extensionEnabled(OESTextureFloatName)) {
+        if (extensionEnabled(OESTextureFloatName) || extensionEnabled(OESTextureHalfFloatName)) {
             if (buffer && buffer->type() != DOMArrayBufferView::TypeFloat32) {
                 synthesizeGLError(GL_INVALID_OPERATION, "readPixels", "type FLOAT but ArrayBufferView not Float32Array");
                 return false;
@@ -5128,8 +5128,21 @@ ScriptValue WebGLRenderingContextBase::getFloatParameter(ScriptState* scriptStat
 ScriptValue WebGLRenderingContextBase::getIntParameter(ScriptState* scriptState, GLenum pname)
 {
     GLint value = 0;
-    if (!isContextLost())
+    if (!isContextLost()) {
         contextGL()->GetIntegerv(pname, &value);
+        switch (pname) {
+        case GL_IMPLEMENTATION_COLOR_READ_FORMAT:
+        case GL_IMPLEMENTATION_COLOR_READ_TYPE:
+            if (value == 0) {
+                // This indicates read framebuffer is incomplete and an
+                // INVALID_OPERATION has been generated.
+                return ScriptValue::createNull(scriptState);
+            }
+            break;
+        default:
+            break;
+        }
+    }
     return WebGLAny(scriptState, value);
 }