[css-timing-functions-1] Couple of minor typos

Author: ChumpChief

css-timing-functions/Overview.bs

@@ -28,7 +28,7 @@ Introduction {#introduction}
 
 It is often desirable to control the rate at which an animation progresses.
 For example, gradually increasing the speed at which an element moves can
-give the element a sense weight as it appears to gather momentum.
+give the element a sense of weight as it appears to gather momentum.
 This can be used to produce user intuitive interface elements or convincing
 cartoon props that behave like their physical counterparts.
 Alternatively, it is sometimes desirable for animation to move forwards in
@@ -58,7 +58,7 @@ A <dfn export>timing function</dfn> takes an [=input progress value=] and
 produces an [=output progress value=].
 
 A [=timing function=] must be a pure function meaning that for a given set of
-inputs, it always produce the same [=output progress value=].
+inputs, it always produces the same [=output progress value=].
 
 The <dfn>input progress value</dfn> is a real number in the range [-&infin;,
 &infin;].