#2278 allow expressions for literal values in root instance props
#2287 fix transition hooks call context to be consistent with compilation scope rules
#2291 fix CSP build minification error
#2297 avoid implicit reference to global variables (fix usage in NW.js)
#2300 fix currency filter negative number display
#2305 fix multiple activate hooks merging
#2312 fix named/default slot distribution when a slot is passed down as content to a child
#2345 improve real custom element detection to avoid unnecessary warnings
#2348 fix slot with v-if fallback compilation scope
#2364 fix
expression parsing with ES6 template strings (note: this only fixes the
expression parsing, it still depends on whether the browser natively
supports ES6 template strings)
#2366 fix custom terminal directive with global mixin (@rhyzx)
#2393 fix observing objects with enumerable but non-configurable properties (@saul)
#2396 fix SVG element transition detection in Chrome
#2400 fix v-model with debounce value not immediately synced on form submission
#2406 fix SVG element fragment linker caching in IE
#2407 fix v-bind value for non-boolean enumerable attributes that expects "true" or "false"values, e.g. draggable
#2411 null or undefined should not trigger type check warning for a non-required prop
