fix(input): prevent the floating label from overflowing

The calc that was used to truncate the long input labels was actually making them longer.

Closes #7403.

Author: crisbeto

src/components/input/input.scss

@@ -285,7 +285,7 @@ md-input-container {
       transform: translate3d(0, $input-label-float-offset, 0) scale($input-label-float-scale);
       transition: transform $swift-ease-out-timing-function $swift-ease-out-duration,
                   width $swift-ease-out-timing-function $swift-ease-out-duration;
-      width: calc((100% - #{$input-label-float-width}) / #{$input-label-float-scale});
+      width: calc((100% - #{$input-label-float-width}) * #{$input-label-float-scale});
     }
   }
 
@@ -349,7 +349,7 @@ md-input-container {
       > label {
         &:not(.md-no-float):not(._md-container-ignore),
         .md-placeholder {
-          width: calc((100% - #{$icon-offset} - #{$input-label-float-width}) / #{$input-label-float-scale});
+          width: calc((100% - #{$icon-offset} - #{$input-label-float-width}) * #{$input-label-float-scale});
         }
       }
     }
@@ -394,7 +394,7 @@ md-input-container {
       > label {
         &:not(.md-no-float):not(._md-container-ignore),
         .md-placeholder {
-          width: calc((100% - (#{$icon-offset} * 2)) / #{$input-label-float-scale});
+          width: calc((100% - (#{$icon-offset} * 2)) * #{$input-label-float-scale});
         }
       }
     }