message: Fix ios building extrusion bug
diff: @@ -22,7 +22,7 @@ varying float vExtrusionRatio;
  // Cancel extrusionRatio (meaning, force to 1) if extrusionAxisLen < MIN_BUILDING_HEIGHT.
  const float MIN_BUILDING_HEIGHT_SQUARED = ${MIN_BUILDING_HEIGHT_SQUARED};
  float extrusionAxisLenSquared = dot(extrusionAxis.xyz, extrusionAxis.xyz);
  -vExtrusionRatio = max(1.0 - step(MIN_BUILDING_HEIGHT_SQUARED, extrusionAxisLenSquared), extrusionRatio);
  +vExtrusionRatio = (extrusionAxisLenSquared < MIN_BUILDING_HEIGHT_SQUARED) ? 1.0 : extrusionRatio;
  transformed = transformed + extrusionAxis.xyz * (vExtrusionRatio - 1.0);
  vExtrusionAxis = vec4(normalMatrix * extrusionAxis.xyz, extrusionAxis.w);
  