2.1.1 [HTML] Section 5.2.2, Specifying the character encoding
To sum up, conforming user agents must observe the following priorities when determining a document's character encoding (from highest priority to lowest): 1. An HTTP "charset" parameter in a "Content-Type" field. 2. A META declaration with "http-equiv" set to "Content-Type" and a value set for "charset". 3. The charset attribute set on an element that designates an external resource.
Quirks Mode, IE7 Mode, and IE8 Mode (All Versions)
The determination of a document’s character encoding is not based on the charset attribute on the LINK or anchor tag. Instead, it is based on the charset of the retrieved resource.