Remove calc support from media queries

Gecko currently doesn't support calc inside media queries. We should
also remove the calc support temporarily for parity with gecko. We can
add this support back in next releases.

components/style/gecko/media_queries.rs

@@ -32,8 +32,9 @@ use string_cache::Atom;
 use style_traits::{CSSPixel, DevicePixel};
 use style_traits::{ToCss, ParseError, StyleParseError};
 use style_traits::viewport::ViewportConstraints;
-use values::{CSSFloat, specified, CustomIdent, serialize_dimension};
+use values::{CSSFloat, CustomIdent, serialize_dimension};
 use values::computed::{self, ToComputedValue};
+use values::specified::Length;
 
 /// The `Device` in Gecko wraps a pres context, has a default values computed,
 /// and contains all the viewport rule state.
@@ -304,7 +305,7 @@ impl ToCss for Resolution {
 #[derive(Clone, Debug, PartialEq)]
 pub enum MediaExpressionValue {
     /// A length.
-    Length(specified::Length),
+    Length(Length),
     /// A (non-negative) integer.
     Integer(u32),
     /// A floating point value.
@@ -339,7 +340,7 @@ impl MediaExpressionValue {
             nsMediaFeature_ValueType::eLength => {
                 debug_assert!(css_value.mUnit == nsCSSUnit::eCSSUnit_Pixel);
                 let pixels = css_value.float_unchecked();
-                Some(MediaExpressionValue::Length(specified::Length::from_px(pixels)))
+                Some(MediaExpressionValue::Length(Length::from_px(pixels)))
             }
             nsMediaFeature_ValueType::eInteger => {
                 let i = css_value.integer_unchecked();
@@ -555,10 +556,20 @@ impl Expression {
 
             let value = match feature.mValueType {
                 nsMediaFeature_ValueType::eLength => {
-                    MediaExpressionValue::Length(
-                        specified::Length::parse_non_negative(context, input)?)
+                    let length = Length::parse_non_negative(context, input)?;
+                    // FIXME(canaltinova): See bug 1396057. Gecko doesn't support calc
+                    // inside media queries. This check is for temporarily remove it
+                    // for parity with gecko. We should remove this check when we want
+                    // to support it.
+                    if let Length::Calc(_) = length {
+                        return Err(StyleParseError::UnspecifiedError.into())
+                    }
+                    MediaExpressionValue::Length(length)
                 },
                 nsMediaFeature_ValueType::eInteger => {
+                    // FIXME(emilio): We should use `Integer::parse` to handle `calc`
+                    // properly in integer expressions. Note that calc is still not
+                    // supported in media queries per FIXME above.
                     let i = input.expect_integer()?;
                     if i < 0 {
                         return Err(StyleParseError::UnspecifiedError.into())